@article{MAN_1993__295_1_165042,
     author = {Mario J. Micallef and Jon G. Wolfson},
     title = {The second variation of area of minimal surfaces in four-manifolds.},
     journal = {Mathematische Annalen},
     pages = {245--268},
     publisher = {mathdoc},
     volume = {295},
     number = {1},
     year = {1993},
     zbl = {0788.58016},
     url = {http://geodesic.mathdoc.fr/item/MAN_1993__295_1_165042/}
}