In this paper we give the complete explicit description of the holomorphicautomorphisms of any nondegenerate CR-quadric Q of arbitrary CRdimensionand codimension and of Siegel domains of second kind with not necessarilyLevi-nondegenerate Silov-boundary.We introduce a family of k-dimensional chains (k = codim Q), the analoguesof one-dimensional Chern-Moser chains for hyperquadrics.We also analyse some different types of rigid quadrics
