@article{MM2_1986__57_155197,
     author = {Friedrich W. Kn\"oller and Holger Heidrich},
     title = {\"Uber die {Fundamentalgruppen} {Siegelscher} {Modulvariet\"aten} vom {Grade} 2.},
     journal = {Manuscripta mathematica},
     pages = {249--262},
     publisher = {mathdoc},
     volume = {57},
     year = {1986},
     zbl = {0596.14030},
     url = {http://geodesic.mathdoc.fr/item/MM2_1986__57_155197/}
}