@article{RSMUP_1969__42__341_0,
     author = {Holmes, Charles S.},
     title = {Projectivities of free products},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {341--387},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {42},
     year = {1969},
     mrnumber = {268286},
     zbl = {0245.20031},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_1969__42__341_0/}
}