Ericksen, Julia A и др. Fertility Patterns and Trends among the Old Order Amish // Population Studies 33 (2). юли 1979. DOI:10.2307/2173531. OCLC 39648293. с. 255 – 76.
Ericksen, Julia A и др. Fertility Patterns and Trends among the Old Order Amish // Population Studies 33 (2). юли 1979. DOI:10.2307/2173531. OCLC 39648293. с. 255 – 76.