Unitary actions of $S^1$ on complex projective spaces
O. R. Musin

References
1.	W. Iberkleid, T. Petrie, Smooth $S^1$-manifolds, Lecture Notes in Math., 557, Springer, Berlin, 1976
2.	I. M. Krichever, “Prepyatstviya k suschestvovaniyu $S^1$-deistvii. Bordizmy razvetvlennykh nakryvayuschikh”, Izv. AN, ser. matem., 40:4 (1976), 828–844
3.	I. M. Krichever, “Ob invariantnosti kharakteristicheskikh klassov dlya mnogoobrazii gomotopicheskogo tipa $\mathbb{C}P^n$”, UMN, 28:4 (1973), 245–246