SUMMARY A GC-MS method with serially coupled capillary columns containing consecutive nonpolar, semipolar, and polar stationary phases has been used for determination of fatty acids in garlic (Allium sativum). Saturated (14:0, 15:0, 16:0, and 18:0), unsaturated (7-16:1, 7-18:1, 9-18:1, 9,12-18:2,  9,12,15-18:3), and unusual cyclic sulfur-containing fatty acids in garlic were identified by GC-MS

L O Hanuš

S Abu-Lafi

V M Dembitsky

CiteSeerX

 
 
 
 
 
 
 
ACTA CHROMATOGRAPHICA, NO. 18, 2007 
SEPARATION OF SULFUR-CONTAINING 
FATTY ACIDS FROM GARLIC, ALLIUM SATIVUM, 
USING SERIALLY COUPLED CAPILLARY COLUMNS 
WITH CONSECUTIVE NONPOLAR, SEMIPOLAR, 
AND POLAR STATIONARY PHASES  
 
V. M. Dembitsky1, S. Abu-Lafi2, and L. O. Hanuš1,* 
 
1Department of Medicinal Chemistry and Natural Products, School of Pharmacy, 
P.O. Box 12065, The Hebrew University of Jerusalem, Jerusalem 91120, Israel 
2Department of Chemistry and Chemical Technology, Al-Quds University, Abu-Deis, 
P.O. Box 20002, West Bank, Palestinian Authority 
 
 
SUMMARY 
 
 A GC–MS method with serially coupled capillary columns contai-
ning consecutive nonpolar, semipolar, and polar stationary phases has been 
used for determination of fatty acids in garlic (Allium sativum). Saturated 
(14:0, 15:0, 16:0, and 18:0), unsaturated (7-16:1, 7-18:1, 9-18:1, 9,12-18:2, 
9,12,15-18:3), and unusual cyclic sulfur-containing fatty acids in garlic 
were identified by GC–MS. 
 
INTRODUCTION 
 
 Sulfolipids were originally discovered in diatom species, in 1966, 
by Morris Kates [1–3]. High levels of these sulfolipids have been found in 
the alga Ochromonas danica (Chrysophyceae, Chrysophyta) where they con-
stitute 15% of total lipids and 3% of the dry weight of heterotrophically 
grown, stationary-phase cells [4,5]. More recently, sulfolipids have also 
been identified in more than 30 species of green (Chlorophyceae), brown 
(Phaeophyceae), and red (Rhodophyceae) freshwater and marine macro- 
phytic algae [6–8] and other microalgal species [9–14]. The presence of 
sulfolipids in algae, diatoms, and marine invertebrates has been reported 
in several review articles [15–20]. 
 
––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––– 
 
 Some parts of this paper were presented at the 7th Congress of the International Society 
for the Study of Fatty Acids and Lipids, July 2006, Cairns, North Queensland, Australia, 
and at the 4th Euro Fed Lipid Congress, October 2006, Madrid, Spain 
 - 206 -
 
 Sulfur-containing fatty (carboxylic) acids (SFA) are rare in nature. 
Several sulfur-containing fatty acids have been isolated from garlic; they 
are also produced by some microorganisms. 1,2-Dithiacyclopentane-3-car-
boxylic acid (also known as tetra-norlipoic or tetranorthioctic acid) was re-
cently isolated from two varieties of garlic (Allium sativum var. sativum 
and Allium ampeloprasum var. holmens) cultivated in the North of Iran 
[21,22]. 3-(Methylsulfinyl)alanine has been detected in different onion cul-
tivars (Allium cepa) [23] and is present among the free amino acids in two 
species of Allium sativum var. opioscorodon (hardneck) and Allium sativum 
var. sativum (softneck) [24]. (S)-2-Propenyl-D-cysteine has been isolated 
from garlic (Aomori Prefecture, Japan) after heating from 30 to 65°C [25]. 
3-Allylthiopropionic acid has been detected among the volatile organic 
compounds obtained from fresh and frozen dried garlic (Allium sativum, 
collected in South Korea) [26] and in this study. Three-hundred and forty 
Streptomyces species grown in the presence of DL-methionine synthesized 
3-methylthiopropionic and trans-3-methylthioacrylic acids [27]. 3-Methyl-
thioacrylic acid, a potential herbicide, also produced by Streptomyces ka-
sugaensis SK 619, inhibited growth of Photobacterium phosphoreum at 
concentrations of 50–200 µg per disk [28]. Derivatives of 3-methylthiopro-
pionic and trans-3-methylthioacrylic acids, named entadamide A and enta-
damide B, have been isolated from the dry seeds of Entada phaseoloides 
[29,30]. Their glycosides were obtained from the same plant [31]. Enta-
damide C and entadamide A has been isolated from the leaves of Entada 
phaseoloides [32]. 
 The structure of 4-thiapentanoic (methylthiopropionic) acid formed 
from methionine has also been reported [33,34]. Three isomeric epithio 
stearic acids have been isolated as minor components of canola oil [35]. 
The biological activity of these fatty acids and some their medicinal ef-
fects have been reported recently [36]. 
 In this study we continued our investigation of food products [37] 
and attempted to characterize the sulfolipids of garlic which grows in the 
Middle East. 
 
EXPERIMENTAL 
 
Samples 
 
 Garlic cloves (Allium sativum) were purchased in local stores in Je-
rusalem. The garlic was obtained directly from the growers – Vegetable 
 - 207 -
 
Beth-Shemesh Farm, near Jerusalem. For irrigation Vegetable Beth-She-
mesh Farm uses underground water containing a high concentration of H2S 
[37]. 
 
Extraction and Preparation of Methyl Esters 
 
 Fresh garlic cloves (1.8 kg) were peeled and the kernels were ho-
mogenized at high speed. The resulting suspension was filtered, at +2°C, 
through gauze then a large porous membrane. Fatty acids were extracted 
three times with a cold (−5°C) 1:1 (v/v) mixture of dichloromethane and me-
thanol. The combined dichloromethane–methanol extracts were evapora-
ted under reduced pressure at 10°C. The garlic oil obtained was divided 
into two parts, one of which was agitated with benzene and sodium me-
thoxide in methanol for 2 h at room temperature and left to stand over-
night. Methyl esters of the fatty acids were obtained by transesterification, 
as described elsewhere [33,34], and crystallized overnight at 0°C from a 
solution of methanol and urea (50 g urea dissolved in 300 mL methanol). 
The precipitate was filtered, washed with cold methanol saturated with 
urea, and, after dilution with water, the methyl esters were extracted with 
diethyl ether. Methyl esters of both fractions were separated on TLC pla-
tes (20 cm × 20 cm, 0.25 mm, with fluorescent indicator; Merck) using he-
xane–diethyl ether–acetic acid 80:20:10 (v/v) as mobile phase. The two 
main zones (visible under UV illumination) on TLC plates were scraped 
from the plate, extracted with diethyl ether, and stored at −20°C until GC–
MS analysis. 
 
GC–MS 
 
 GC–MS was performed with a Hewlett-Packard (HP) 5890 (series 
II) chromatograph modified for use with glass capillary columns and coup-
led with an HP 5971B MSD mass-selective detector. Sulfur compounds 
and fatty acid methyl esters were analyzed by gas chromatography on three 
coupled capillary columns, as described elsewhere [16] – first, a 10 m × 
0.32 mm i.d. column coated with a 0.25 µm film of HP-5, second a 30 m 
× 0.32 mm i.d. column coated with a 0.25 µm film of RTX-1701 (Restek, 
PA, USA), and third a 30 m × 0.32 mm column coated with a 0.25 µm film 
of HP-FFAP. The GC oven was maintained at 40°C for 2 min then pro-
grammed at 2° min−1 to 300°C which was maintained for 20 min. The 
injector was used in splitless mode at 180°C. Helium was used as carrier 
gas at a flow rate of 25 cm s−1. The MS detector was operated at 194°C, 
 - 208 -
 
with an ionization energy of 70 eV. Scanning between m/z 30 and 650 was 
performed at 0.9 scans s−1. The solvent delay was 10 min. The fatty acid 
methyl esters were identified from their mass spectral fragmentation and 
by use of the Wiley (7th edition) mass spectral library search. Mass spec-
tra obtained for SFA were compared with those obtained from synthesized 
analogues. 
 
RESULTS AND DISCUSSION 
 
 Sulfur compounds and methyl esters of fatty acids from garlic we-
re analyzed by GC–MS on three coupled capillary columns [38]. By using 
both a typical injection port and also ‘cryogenic GC–MS’ analysis [37] we 
identified 2-vinyl-4H-1,3-dithiin and 3-vinyl-4H-1,2-dithiin as the two 
major compounds, in addition to di-2-propenyl trisulfide, in garlic extract. 
Separation of the sulfur compounds and the fatty acid methyl esters is 
shown in Fig. 1. Among the fatty acids identified are palmitic and stearic 
 
 
Fig. 1 
 
GC–MS chromatogram of organosulfur compounds and methyl esters of fatty acids from 
garlic (Allium sativum). Separation was achieved by use of serially coupled capillary co-
lumns with stationary phases of different polarity. A. Full chromatogram (up to 120 min). 
B. Part of the chromatogram showing separation of the fatty acid methyl esters. C. Part 
of the chromatogram showing separation of the C18 family of acids, including the novel 
SFA (1, 2, and 3) 
 - 209 -
 
acids as major compounds, with C14:0, C15:0, 7-16:1, 7-18:1, 9-18:1, 9,12-
18:2, 9,12,15-18:3, and three novel cyclic SFA – 8-(5-hexylthiophen-2-
yl)octanoic acid, 1, 8-(5-hexyl-tetrahydrothiophen-2-yl)octanoic acid, 2, and 
8-(6-pentyl-tetrahydro-2H-thiopyran-2-yl)octanoic acid), 3. The structures 
of SFA isolated from garlic and from other plants are shown in Fig. 2. 
Mass spectra of these SFA were obtained and are shown in Fig. 3. 
 
S
COOH18
18
18
9
1
1
2
3
4
5
6
 
Fig. 2 
 
Thiopyran and thiophene derivative
nola oil (4, 5, 6) 
 
 8-(5-Hexylthiophen-2-y
characterized by the presence
of the thiophene ring of the a
M − 31 fragment (loss of a m
cular ion (m/z 324). β-Cleavag
se and the relative abundance 
chains and transfer of one hyd
 
 
S
COOH
9
2
s
 
l
e
o
S
COOH
9
3
S
COOH
9
4
S COOH8
5
S
COOH
7
6   and SFA isolated from garlic (1, 2, 3) and from ca-
l)octanoic acid methyl ester (1, Fig. 3A) was 
of a major fragment formed by β-cleavage 
kylcarbomethyl moiety (m/z 181), from the 
thoxy group, m/z 293), and from the mole-
e of the alkyl moiety (m/z 253) is less inten-
f this ion is also reduced. Loss of both side-
rogen atom to the thiophene ring gives rise 
- 210 -
 
 
 
 
 
 
 
Fig. 3 
 
Mass spectral fragmentation pathways proposed for the three unusual C18 sulfur-contai-
ning fatty acids isolated from garlic. Further details of these fragmentations are given in 
the text. 
 - 211 -
 
to secondary fragments (m/z 97, 111, and 123). The McLafferty rearrange-
ment ion (m/z 74) for the carboxymethyl group is not significant and frag-
mentation of the whole molecule is determined by the thiophene ring struc-
ture. 
 Fragmentation of the methyl ester of 8-(5-hexyltetrahydrothiophen-
2-yl)octanoic acid (2, Fig. 3B) furnished two main fragments, m/z 243 and 
171, produced by α-cleavage of the ring of the alkyl and alkylcarboxyme-
thyl moieties, respectively. Cleavage of both moieties and subsequent hy-
drogen transfer to the thiolane ring gives ions of m/z 87 and 101. Frag-
mentation through the ring gives ions of m/z 129 and 201. 
 The major fragmentation of 8-(6-pentyl-tetrahydro-2H-thiopyran-
2-yl)octanoic acid methyl ester (3, Fig 13C) is similar to that of the methyl 
ester of the alkylthiolane acid (2, Fig. 1B). α-Cleavage of the side chains 
of the ring gives fragments of m/z 171 and 257. Loss of both chains and 
hydrogen transfer to the ring gives an ion of m/z 101. Fragmentation 
through the ring gives ions of m/z 115 and 201. The mass spectra obtained 
for all the SFA were compared with spectra of sulfur-containing com-
pounds isolated from sedimentary organic matter and crude oil [39–42]. 
 Epithio acid structures may be related to furanoid fatty acids with 
oxygen in the ring in lieu of sulfur, which are known, and found in oils 
from algae, plants, fish, and invertebrates [43,44]. A mechanism for their 
formation in nature has been published [45,46]. 
 The two cyclic SFA 1 and 2 contain thiophene and tetrahydrothio-
phene rings, respectively. Derivatives of thiophene are widespread in plant 
species and also identified in the genus Allium: A. chinense [47], A. ampe-
loprasum var. bulga [48], A. albidum, A. altaicum, A. carolinianum, A. hy-
menorrhizum, A. lineare, A. nutans, A. ramosum, and A. tuberosum [49], A. 
cepa and A. porum [50], A. sativum var. sativum and A. sativum var. hol-
mense [21,22], among others. 
 The cyclic SFA 3 contains a thiopyran ring. Thiopyran derivatives 
are rare in nature, but have been detected in garlic and some other plants. 
3,6-Dihydro-2H-thiopyran and 2H-thiopyran-3(6H)-one have been detec-
ted in dried Jimbu (Allium wallichii) [51]. Derivatives of thiophene have 
been isolated from fresh Greek garlic (Allium sativum) cloves [52] and from 
Chinese garlic [53]. Tetrahydro-2H-thiopyran-2-carboxylic acid has been 
isolated from the rod-shaped bacterium Tubercle bacillus [54]. 
 Three isomeric epithio stearic acids, 9,12 (4), 8,11 (5), and 7,10 
(6), each with a methyl substituent on the ring (Fig. 2), have been isolated 
 - 212 -
 
as minor sulfur-bearing fatty acids from unprocessed canola oil (Celtic 
mythology) [35]. 
 Analysis of garlic extracts has shown that samples collected from 
different locations have different fatty acid profiles. The flavor compounds 
of Allium mairei collected in Kunming Province, China were prepared by 
use of simultaneous distillation and extraction equipment. Six fatty acids 
were detected: C7:0, C9:0, C14:0, C15:0, C16:0, and C18:0 [55,56]. Ana-
lysis of the fatty acids of the seed oil of Allium tuberosum collected in 
Shanghai Province revealed the presence of many important fatty acids, in-
cluding linoleic (9,12-18:2; the amount varying in different samples from 
57.0 to 71.6%), palmitic (C16:0, 6.6–9.7%), 9-18:1, 11-20:1, C20:0, C22:0, 
C23:0, and C24:0 [57]. The flowers of Allium tenuissimum from Shanxi 
Province contain C16:0, C19:0, and 9,12-18:2 as major fatty acids [58]. 
 The unique fatty acid (Z,Z)-2,5-octadecadienoic acid has been iden-
tified with C16:0, 11,14-eicosadienoic, and 2,3-dihydroxybutanedioic acids 
in the aerial part of Allium tuberosum [59]. 
 
CONCLUSIONS 
 
 We have demonstrated that garlic contains low levels of cyclic 
SFA. It is possible that the SFA in garlic oil are derived from stable polar 
lipids and/or triacylglycerides. We have also found that the polar lipid frac-
tion contains other sulfur compounds. Identification of these sulfolipid com-
pounds is in progress. 
 
 
REFERENCES 
 
[1] M. Kates and B.E. Volkani, Biochim. Biophys. Acta, 
116, 264 (1966) 
[2] M. Kates and B.E. Volkani, Z. Pflanzenphysiol., 60, 19 (1968) 
[3] R. Anderson, M. Kates, and B.E. Volkani, Biochim. Biophys. Acta, 
528, 89 (1978) 
[4] J. Elovson and P.R. Vagelos, PNSA, 62, 957 (1969) 
[5] T.H. Haines, M. Pousada, B. Stern, and G.L. Mayers, Biochem. J., 
113, 565 (1969) 
[6] E.I. Mercer and C.L. Davies, Phytochemistry, 18, 457 (1979) 
[7] J.L. Harwood, Adv. Photosynth., 6, 53 (1998) 
 - 213 -
 
[8] R.J. Henderson, E.E. MacKinlay, P. Hodgson, and J.L. Harwood, 
J. Exp. Bot., 41, 723 (1990) 
[9] E.I. Mercer and C.L. Davies, Phytochemistry, 13, 1607 (1974) 
[10] E.I. Mercer and C.L. Davies, Phytochemistry, 14, 1545 (1975) 
[11] J. Elovson, Biochemistry, 13, 3483 (1974) 
[12] J.L. Chen, P.J. Proteau, M.A. Roberts, W.H. Gerwick, D.L. Slate, 
and R.H. Lee, J. Nat: Prod., 57, 524 (1994) 
[13] J. Elovson and P.R. Vagelos, Biochemistry, 9, 3110 (1970) 
[14] I. Winicov, Diss. Abstr. Int. B, 46, 1552 (1986) 
[15] M. Kates, Sulfolipids. In: Marine Biogenic Lipids, Fats, and Oils, 
Vol. 1, R.G. Ackman, Ed., CRC Press, Boca Raton, FL, 1989, 
pp. 389–427 
[16] J.M. Kornprobst, S. Sallenave, and G. Barnathan, Comp. Biochem. 
Physiol., 119B, 1 (1998) 
[17] V.M. Dembitsky and M. Srebnik, Prog. Lipid Res., 41, 315 (2002) 
[18] A.A. Benson, Adv. Lipid Res., 1, 387 (1963) 
[19] D.A. Rees, Ann. Rep. Prog. Chem., 62, 469 (1966) 
[20] D.J. Hanahan and G.A. Thompson Jr, Ann. Rev. Biochem., 
32, 215 (1963) 
[21] P.R. Kharazi, Phosphorus, Sulfur, Silicon Related Elem., 
180, 1399 (2005) 
[22] P.R. Kharazi and G. Peyvast, Asian J. Chem., 17, 219 (2005) 
[23] J. Resemann and R. Carle, J. Food Agric. Environ., 1, 104 (2003) 
[24] J. Lee and J.M. Harnly, J. Agric. Food. Chem., 53, 9100 (2005) 
[25] Y. Yamazaki, Production of Processed Garlic. Japan Kokai Tokkyo 
Koho, 20 pp. Japanese Patent: JP 2005278635 A2 20051013. 
Application: JP 2004-381423 20041228 (2005) 
[26] Y.-S. Kim, H.-Y. Seo, K.-M. No, S.-L. Shim, S.-H. Yang, 
E.-R. Park, and K.-S. Kim, Han’guk Sikp’um Yongyang Kwahak 
Hoechi (S. Korea), 34, 885 (2005) 
[27] K. Arima, T. Yamashita, J. Hosoda, and G. Tamura, Agric. Biol. 
Chem., 34, 1178 (1970) 
[28] M. Sturdikova, B. Proksa, M. Rosenberg, and J. Fuska, Lett. Appl. 
Microbiol., 18, 165 (1994) 
[29] F. Ikegami, I. Shibasaki, S. Ohmiya, N. Ruangrungsi, 
and I. Murakoshi, Chem. Pharm. Bull., 33, 5153 (1985) 
[30] F. Ikegami, S. Ohmiya, N. Ruangrungsi, S. Sakai, and I. Murakoshi, 
Phytochemistry, 26, 1525 (1987) 
 - 214 -
 
[31] J. Dai, L.B.S. Kardono, S. Tsauri, K. Padmawinata, J.M. Pezzuto, 
and A.D. Kinghorn, Phytochemistry, 30, 3749 (1991) 
[32] F. Ikegami, T. Sekine, S. Duangteraprecha, N. Matsushita, 
N. Matsuda, N. Ruangrungsi, and I. Murakoshi, Phytochemistry, 
28, 881 (1989) 
[33] P.W.D. Scislowski, B.M. Hokland, D. van Thienen, J. Bremer, 
and E.J. Davis, Biochem. J., 247, 35 (1987) 
[34] S. Skrede, H.N. Sørensen, L.N. Larsen, H.H. Steineger, K. Høvik, 
Ø.S. Spydevold, R. Horn, and J. Bremer, Biochim. Biophys. Acta, 
1344, 115 (1997) 
[35] R.C. Wijesundera and R.G. Ackman, J. Am. Oil Chem. Soc., 
65, 959 (1988) 
[36] J. Bremer, Prog. Lipid Res., 40, 231 (2001) 
[37] S. Abu-Lafi, J.W. Dembicki, P. Goldshlag, L. Hanuš, 
and V.M. Dembitsky, J. Food Comp. Anal., 17, 235 (2004) 
[38] V.M. Dembitsky, I. Shkrob, and I. Dor, J. Chromatogr. A, 
862, 221 (1999) 
[39] W.L. Orr and J.S. Sinninghe Damste, Geochemistry of Sulfur 
in Petroleum Systems. In: W.L. Orr and C.M. White (Eds) 
Geochemistry of Sulfur in Fossil Fuels, ACS Symp. Series, Am. 
Chem. Soc., No. 249, pp. 2–29, 1990 
[40] J.S. Sinninghe Damste, W.I.C. Rijpstra, J.W. de Leew, 
and P.A. Schenk, Geochim. Cosmochim. Acta, 53, 1323 (1989) 
[41] J.S. Sinninghe Damste, H.L. ten Haven, J.W. de Leew, 
and P.A. Schenk, In: D. Leythauser and J. Rullkotter (Eds) Advances 
in Organic Geochemistry 1985, Pergamon Press, pp. 791–805, 1986 
[42] M.P. Koopmans, J.S. Sinninghe Damste, M.D. Lewan, 
and J.W. de Leeuw, Org. Geochem., 23, 583 (1995) 
[43] A. Batna and G. Spiteller, Phytochemistry, 32, 311 (1993) 
[44] I.A. Sigrist, G.G.G. Manzardo, and R. Amado, Spec. Pub. Royal 
Soc. Chem., 269, 237 (2001) 
[45] G. Spiteller, Lipids, 40, 755 (2005) 
[46] G. Spiteller, J. Lipid Mediators, 7, 199 (1993) 
[47] J. Bai, Y. Wu, X. Mo, S. Zheng, W. Chen, and L. Xia, Shipin Kexue 
(Beijing, China), 25, 146 (2004) 
[48] G.S. Nielsen and L. Poll, J. Agric. Food Chem., 52, 1642 (2004) 
[49] H. Schulz and H. Krueger, J. Herbs Spices Med. Plants, 
9, 205 (2002) 
 
 - 215 -
 
[50] M. Albrand, P. Dubois, P. Etievant, R. Gelin, and B. Tokarska, 
J. Agric. Food Chem., 28, 1037 (1980) 
[51] A. Kattel and J.A. Maga, Dev. Food Sci., 37A, 919 (1995) 
[52] A.C. Kimbaris, N.G. Siatis, D.J. Daferera, P.A. Tarantilis, 
C.S. Pappas, and M.G. Polissiou, Ultrason. Sonochem., 
13, 54 (2006) 
[53] Y. Zhang, Tianran Chanwu Yanjiu Yu Kaifa, 9, 53 (1997) 
[54] J. Cason, G.L. Lange, W.T. Miller, and A. Weiss, Tetrahedron, 
20, 91 (1964) 
[55] X. Chen, D. Shi, and S. Chen, Jingxi Huagong, 22, 373 (2005) 
[56] W.W. Christie, E.Y. Brechany, M.S.F. Lie Ken Jie, and O. Bakare, 
Biomed. Environ. Mass Spectrom., 20, 629 (1991) 
[57] G. Hu, Y. Lu, and D. Wei, Biores. Technol., 96, 1630 (2005) 
[58] Q. Mu, Xibei Zhiwu Xuebao, 21, 1204 (2001) 
[59] Y. Yi, D. Lu, and M. Yin, Zhongguo Yaoxue Zazhi (Beijing, 
China), 26, 648 (1991) 
 
 
 - 216 -


SEPARATION OF SULFUR-CONTAINING FATTY ACIDS FROM GARLIC, ALLIUM SATIVUM, USING SERIALLY COUPLED CAPILLARY COLUMNS WITH CONSECUTIVE NONPOLAR, SEMIPOLAR, AND POLAR STATIONARY PHASES

http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=2465429F70DE6099163CB4FD29D09DA5?doi=10.1.1.1071.7139&rep=rep1&type=pdf

SEPARATION OF SULFUR-CONTAINING FATTY ACIDS FROM GARLIC, ALLIUM SATIVUM, USING SERIALLY COUPLED CAPILLARY COLUMNS WITH CONSECUTIVE NONPOLAR, SEMIPOLAR, AND POLAR STATIONARY PHASES

Abstract

Similar works

Full text

Available Versions

CiteSeerX