TY  - RPRT
TI  - Periodic solutions to nonautonomous difference equations.
AU  - M E Clark
AU  - L J Gross
PY  - 1990
DO  - 10.1016/0025-5564(90)90057-6
UR  - https://pubmed.ncbi.nlm.nih.gov/2134487/
ID  - 2134487
ER  -