@article{01872691, title = {On 4-fold covering moves.}, journal = {Geometry \& Topology}, volume = {7}, year = {2003}, pages = {117-145}, doi = {10.2140/agt.2003.3.117}, zbl = {1014.57001}, language = {en}, url = {http://dml.mathdoc.fr/item/01872691} }
Apostolakis, Nikos. On 4-fold covering moves.. Geometry & Topology, Tome 7 (2003) pp. 117-145. doi : 10.2140/agt.2003.3.117. http://gdmltest.u-ga.fr/item/01872691/