MR0213665
Saito, Tosiya
Tosiya SAITO
On an isolated singular point of a non-autonomous periodic system
Funkcialaj Ekvacioj. Serio Internacia
9
1966
199--206
http://fe.math.kobe-u.ac.jp/FE/Free/vol09/fe09-26.pdf
http://fe.math.kobe-u.ac.jp/FE/FE_pdf_with_bookmark/FE01-10-en_KML/fe09-199-206/fe09-199-206.pdf
http://www.ams.org/mathscinet-getitem?mr=MR0213665
fe09-199-206
1966
On an Isolated Singular Point of a Non-Autonomous Periodic System
Saito, Tosiya
Saito, Tosiya