@article{GDZPPN002230321,
title = {The Dirichlet Energy of Mappings with values into the sphere.},
journal = {Manuscripta mathematica},
volume = {64},
year = {1989},
pages = {489-507},
zbl = {0678.49006},
url = {http://dml.mathdoc.fr/item/GDZPPN002230321}
}
Giaquinta, Mariano; Modica, Giuseppe. The Dirichlet Energy of Mappings with values into the sphere.. Manuscripta mathematica, Tome 64 (1989) pp. 489-507. http://gdmltest.u-ga.fr/item/GDZPPN002230321/