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http://www.crookston.org/offices/marriagefamily/nfp
Couple to Couple League (CCL) Sympto-Thermal MethodÂ
https://ccli.org/
Creighton Model Fertility Care System featuring NaPro Technology Method
http://www.creightonmodel.com/index.htmlBillings Ovulation Method of America (BOMA) Method
http://www.boma-usa.org/