1. G. Busetto, On the embedding of core-free projective images of normal subgroups. Ann. Mat. Pura Appl.142, 91?103 (1985).
2. G. Busetto, Proprieta' di immersione dei sottogruppi modulari localmente ciclici nei gruppi. Rend. Sem. Mat. Univ. Padova62, 269?284 (1980).
3. G. Busetto, Sottogruppi normali e proiettivita'. Rend. Sem. Mat. Univ. Padova67, 105?110 (1982).
4. G. Busetto andF. Menegazzo, Groups with soluble factor groups and projectivities. Rend. Sem. Mat. Univ. Padova73, 249?260 (1985).
5. G. Busetto andF. Napolitani, On projectivities of groups. Proceedings of the second international Group Theory conference, Bressanone/Brixen, June 11?17/1989. Rend. Circ. Mat. Palermo23, 45?55 (1990).