@article{10_4153_CMB_1988_010_6,
     author = {Schmidt, E. J. P. Georg},
     title = {On an {Extremal} {Problem} {Involving} {Harmonic} {Functions}},
     journal = {Canadian mathematical bulletin},
     pages = {63--69},
     year = {1988},
     volume = {31},
     number = {1},
     doi = {10.4153/CMB-1988-010-6},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1988-010-6/}
}