@article{03600807, title = {Crosscaps and knots.}, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {1}, year = {1978}, pages = {113-124}, doi = {10.1155/S0161171278000149}, zbl = {0386.57003}, language = {en}, url = {http://dml.mathdoc.fr/item/03600807} }
Clark, Bradd Evans. Crosscaps and knots.. International Journal of Mathematics and Mathematical Sciences, Tome 1 (1978) pp. 113-124. doi : 10.1155/S0161171278000149. http://gdmltest.u-ga.fr/item/03600807/