http://www.crookston.org/offices/marriagefamily/nfp
Couple to Couple League (CCL) Sympto-Thermal Method 
https://ccli.org/
Creighton Model Fertility Care System featuring NaPro Technology Method
http://www.creightonmodel.com/index.html

Billings Ovulation Method of America (BOMA) Method
http://www.boma-usa.org/

Marquette Model (MM) Method
http://nfp.marquette.edu/