Cukierski Apostolate - Includes information on Natural Family Planning, including the ability to order the book "What Every Catholic Couple Should Know". - http://www.cukierski.net/
The Couple to Couple League in Great Britain - Supports Christian marriage through the teaching of Natural Family Planning and the provision of materials supportive of marriage and family life. - http://www.cclgb.org.uk/
Couple to Couple League - Provides information, teaching and support for couples using or wanting to learn about Natural Family Planning. - http://www.ccli.org/