@article{MAN_1978__234_163123,
     author = {Eiji Horikawa},
     title = {On the {Periods} of {Enriques} {Surfaces.} {I.}},
     journal = {Mathematische Annalen},
     pages = {73--88},
     publisher = {mathdoc},
     volume = {234},
     year = {1978},
     zbl = {0358.14020},
     url = {http://geodesic.mathdoc.fr/item/MAN_1978__234_163123/}
}