TY  - RPRT
TI  - Unstable periodic orbits in the parametrically excited pendulum.
AU  - van de Water W
AU  - M Hoppenbrouwers
AU  - F Christiansen
PY  - 1991
DO  - 10.1103/physreva.44.6388
UR  - https://pubmed.ncbi.nlm.nih.gov/9905769/
ID  - 9905769
ER  -