@article{10_4153_CJM_1967_062_6,
     author = {Hartman, Philip},
     title = {On {Homotopic} {Harmonic} {Maps}},
     journal = {Canadian journal of mathematics},
     pages = {673--687},
     year = {1967},
     volume = {19},
     number = {1},
     doi = {10.4153/CJM-1967-062-6},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1967-062-6/}
}