@article{1178225298, author = {Muk\=oyama, Kazuo}, title = {Smooth ${\rm Sp}(2,{\bf R})$-actions on the $4$-sphere}, journal = {Tohoku Math. J. (2)}, volume = {48}, number = {4}, year = {1996}, pages = { 543-560}, language = {en}, url = {http://dml.mathdoc.fr/item/1178225298} }
Mukōyama, Kazuo. Smooth ${\rm Sp}(2,{\bf R})$-actions on the $4$-sphere. Tohoku Math. J. (2), Tome 48 (1996) no. 4, pp. 543-560. http://gdmltest.u-ga.fr/item/1178225298/