(٢) DevBio، A companion to Developmental Biology by Scott Gilbert، Eigth Edition، Sinauer Associates. (٣) Leader LR، Baillie P.The assessment and significance of habituation in normal and high risk pregnancies.J Perinatol ١٩٩١; ١١: ٢٥ - ٩. (٤) Halamek، Louis. "Prenatal Consultation at the Limits of Viability"، NeoReviews، Vol. ٤ No. ٦ (٢٠٠٣) (٥) Baptist Hospital of Miami، Fact Sheet (٢٠٠٦). وانظر: Tiniest Babies [Online] /auth.Iowa University of and Department Pediatric//University of Iowa Carver College of Medicine. -١٨٢ ، ٢٠٠٨. - http://www.medicine.uiowa.edu/tiniestbabies/.