@article{JRAM_1980__319_152284,
     author = {R.C. Gunning},
     title = {On the period classes of {Prym} differentials. {I.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {153--171},
     publisher = {mathdoc},
     volume = {319},
     year = {1980},
     zbl = {0426.30038},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1980__319_152284/}
}