Extrait de : Proceedings of 'ESO Symposium on high resolution imaging', Garching (Germany), October 15-18, 1991SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1991 n.221 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc