@article{GDZPPN002335131, title = {Hyper K\"ahler and quaternionic K\"ahler geometry.}, journal = {Mathematische Annalen}, volume = {291}, year = {1991}, pages = {421-450}, zbl = {0711.53051}, url = {http://dml.mathdoc.fr/item/GDZPPN002335131} }
Swann, Andrew. Hyper Kähler and quaternionic Kähler geometry.. Mathematische Annalen, Tome 291 (1991) pp. 421-450. http://gdmltest.u-ga.fr/item/GDZPPN002335131/