@article{MM2_1979__28_154639,
     author = {Willi J\"ager and Helmut Kaul},
     title = {Uniqueness and {Stability} of {Harmonic} {Maps} and {Their} {Jacobi} {Fields.}},
     journal = {Manuscripta mathematica},
     pages = {269--292},
     publisher = {mathdoc},
     volume = {28},
     year = {1979},
     zbl = {0413.31006},
     url = {http://geodesic.mathdoc.fr/item/MM2_1979__28_154639/}
}