@article{MM2_1989__65_3_155454,
     author = {Mariano Giaquinta and Giuseppe Modica},
     title = {The {Dirichlet} {Energy} of {Mappings} with values into the sphere.},
     journal = {Manuscripta mathematica},
     pages = {489--507},
     publisher = {mathdoc},
     volume = {65},
     number = {3},
     year = {1989},
     zbl = {0678.49006},
     url = {http://geodesic.mathdoc.fr/item/MM2_1989__65_3_155454/}
}