1. Collineation groups strongly irreducible on an oval;Biliotti;Ann. Discrete Math.,1986
2. Some new results on collineation groups preserving an oval of a finite projective plane;Biliotti,1988
3. Difference sets in a finite group;Bruck;Trans. Amer. Math. Soc.,1955
4. Characterizations of semi quadrics, a survey;Buekenhout,1973
5. Characterizations of semi quadrics, a survey;Buekenhout;Atti Accad. Naz. Lincei,1976