@article{10_1017_S0017089500003542,
     author = {Opolka, Hans},
     title = {Projective representations of extra-special p-groups},
     journal = {Glasgow mathematical journal},
     pages = {149--152},
     year = {1978},
     volume = {19},
     number = {2},
     doi = {10.1017/S0017089500003542},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500003542/}
}