Holzapfel, R. The Ball and Some Hilbert Problems. Springer International Publishing.
Style de citation Chicago (17e éd.)Holzapfel, Rolf-Peter. The Ball and Some Hilbert Problems. Cham: Springer International Publishing.
Style de citation MLA (8e éd.)Holzapfel, Rolf-Peter. The Ball and Some Hilbert Problems. Springer International Publishing.
Opozorilo: Ti citati niso vedno 100% točni.