Dr. Janet E. Smith has written on this subject and is usually referred to as the go-to source. She just came out with a brand new book in light of the 50th Anniversary of HV entitled Why Humane Vitae Is Still Right.
Her other books are:
Humanae Vitae – A Generation Later (published in 1991)
Why Humanae Vitae Was Right (published in 1993)
Dr. Angela Franks has written a short (122 pages) book called: Contraception and Catholicism – What The Church Teaches and Why
Christopher West – The Good News About Sex and Marriage
Love, Marriage, and the Catholic Conscience: Understanding the Church’s Teachings on Birth Control by Dietrich Von Hildebrand – Published in 1998
The Archdiocese of Detroit and their Bishops have a series of homilies on HV which you can view here: http://www.aod.org/being-catholic/marriage-and-family/humanae-vitae/
Jenny Uebbing blogs at Mama Needs Coffee and did an entire guest blog series on Living Humanae Vitae – real life stories from couples practicing NFP.