Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{CMH_1969__44_139408, author = {H. Guggenheimer}, title = {Hill {Equations} with {Coexisting} {Periodic} {Solutions,} {II.}}, journal = {Commentarii mathematici Helvetici}, pages = {381--384}, publisher = {mathdoc}, volume = {44}, year = {1969}, zbl = {0186.41003}, url = {http://geodesic.mathdoc.fr/item/CMH_1969__44_139408/} }
H. Guggenheimer. Hill Equations with Coexisting Periodic Solutions, II.. Commentarii mathematici Helvetici, Tome 44 (1969), pp. 381-384. http://geodesic.mathdoc.fr/item/CMH_1969__44_139408/