@article{RSMUP_1972__48__1_0,
     author = {Wehrhahn, Karl H.},
     title = {Projectivities in finite $p$-groups},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {1--13},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {48},
     year = {1972},
     mrnumber = {360815},
     zbl = {0355.20030},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_1972__48__1_0/}
}