@article{JRAM_1981__328_152391,
     author = {Joachim Wehler},
     title = {Versal deformation of {Hopf} surfaces.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {22--32},
     publisher = {mathdoc},
     volume = {328},
     year = {1981},
     zbl = {0459.32009},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1981__328_152391/}
}