TY - JOUR AU - Husby, H; Holm, N V; Gernow, A; Thomsen, S G; Kock, K; Gürtler, H TI - Zygosity, placental membranes and Weinberg's rule in a Danish consecutive twin series JO - Acta Genet Med Gemellol (Roma) VL - 40 PY - 1991 SP - 147 EP - 152 ER -