Brehm 1990, pp.51–56 Brehm, U. (1990), "How to build minimal polyhedral models of the Boy surface", The Mathematical Intelligencer, 12 (4): 51–56, doi:10.1007/BF03024033, S2CID120093360
Brehm 1990, pp.51–56 Brehm, U. (1990), "How to build minimal polyhedral models of the Boy surface", The Mathematical Intelligencer, 12 (4): 51–56, doi:10.1007/BF03024033, S2CID120093360