Yt. Xu et Zm. Guo, Applications of a Z(p) index theory to periodic solutions for a class of functional differential equations, J MATH ANAL, 257(1), 2001, pp. 189-205
By means of a new geometrical index with Z(p) group actions, multiplicity r
esults for a certain class of nonautonomous time periodic functional differ
ential systems are obtained. (C) 2001 Academic Press.