@article{1250520962,
author = {Sakan, Ken-ichi},
title = {Necessary and sufficient conditions for extremality in certain classes of quasiconformal mappings},
journal = {J. Math. Kyoto Univ.},
volume = {26},
number = {4},
year = {1986},
pages = { 31-37},
language = {en},
url = {http://dml.mathdoc.fr/item/1250520962}
}
Sakan, Ken-ichi. Necessary and sufficient conditions for extremality in certain classes of quasiconformal mappings. J. Math. Kyoto Univ., Tome 26 (1986) no. 4, pp. 31-37. http://gdmltest.u-ga.fr/item/1250520962/