Parra-Saavedra MA, Gómez LA, Barrero A, Parra G, Vergara F, Diaz-Yunez I, Gómez M, Bermúdez C, Kontopoulos EV, Quintero RA.
Cervical Consistency Index: A New Concept in Uterine Cervix Evaluation. 
Donald School J Ultrasound Obstet Gynecol 
2011;
5
(4):411-415.