Martínez-Frías ML, Czeizel AE, Rodríguez-Pinilla E, Bermejo E (January 1999). "Smoking during pregnancy and Poland sequence: results of a population-based registry and a case-control registry". Teratology. 59 (1): 35–8. doi:10.1002/(SICI)1096-9926(199901)59:1<35::AID-TERA8>3.0.CO;2-E. PMID9988881.
Martínez-Frías ML, Czeizel AE, Rodríguez-Pinilla E, Bermejo E (January 1999). "Smoking during pregnancy and Poland sequence: results of a population-based registry and a case-control registry". Teratology. 59 (1): 35–8. doi:10.1002/(SICI)1096-9926(199901)59:1<35::AID-TERA8>3.0.CO;2-E. PMID9988881.