@article{GDZPPN002057786,
title = {On the Geometric Definition for Quasiconformal Mappings.},
journal = {Commentarii mathematici Helvetici},
volume = {35},
year = {1961},
pages = {19-32},
zbl = {0104.29903},
url = {http://dml.mathdoc.fr/item/GDZPPN002057786}
}
Väisälä, Jussi; Gehring, F.W. On the Geometric Definition for Quasiconformal Mappings.. Commentarii mathematici Helvetici, Tome 35 (1961) pp. 19-32. http://gdmltest.u-ga.fr/item/GDZPPN002057786/