John Guckenheimer, Yuri A. Kuznetsov. Hopf-Hopf bifurcation. Scholarpedia, 3(8):1856, 2008. [doi]
@article{GuckenheimerK08,
title = {Hopf-Hopf bifurcation},
author = {John Guckenheimer and Yuri A. Kuznetsov},
year = {2008},
url = {http://www.scholarpedia.org/article/Hopf-Hopf_bifurcation},
researchr = {https://researchr.org/publication/GuckenheimerK08},
cites = {0},
citedby = {0},
journal = {Scholarpedia},
volume = {3},
number = {8},
pages = {1856},
}