Norwitz, Errol R.; Schust, Danny J.; Fisher, Susan J. (2001-11-08). "Implantation and the Survival of Early Pregnancy". New England Journal of Medicine. 345 (19): 1400–1408. doi:10.1056/nejmra000763. ISSN0028-4793. PMID11794174.
Norwitz, Errol R.; Schust, Danny J.; Fisher, Susan J. (2001-11-08). "Implantation and the Survival of Early Pregnancy". New England Journal of Medicine. 345 (19): 1400–1408. doi:10.1056/nejmra000763. ISSN0028-4793. PMID11794174.
Norwitz, Errol R.; Schust, Danny J.; Fisher, Susan J. (2001-11-08). "Implantation and the Survival of Early Pregnancy". New England Journal of Medicine. 345 (19): 1400–1408. doi:10.1056/nejmra000763. ISSN0028-4793. PMID11794174.