A retrospective analysis of unfertilized and presumed parthenogentically activated human oocytes demonstrates a high frequency of sperm penetration.
Van Blerkom J, Davis PW, Merriam J. A retrospective analysis of unfertilized and presumed parthenogentically activated human oocytes demonstrates a high frequency of sperm penetration. Hum Reprod. 1994 Dec; 9(12):2381-8.