A great chapter is from Austen Ivereigh's book which you can find here:
How to Defend the Faith Without Raising Your Voice
available at Amazon.com
Also, essential reading for this topic comes from Pope Paul VI's historic 1968 Encyclical,
Humanae Vitae (On Human Life) found here:
Click here to be redirected to Humanae Vitae
ENCYCLICAL LETTER
HUMANAE VITAE
OF THE SUPREME PONTIFF
PAUL VI
TO HIS VENERABLE BROTHERS
THE PATRIARCHS, ARCHBISHOPS, BISHOPS
AND OTHER LOCAL ORDINARIES
IN PEACE AND COMMUNION WITH THE APOSTOLIC SEE,
TO THE CLERGY AND FAITHFUL OF THE WHOLE CATHOLIC WORLD, AND TO ALL MEN OF GOOD WILL,
ON THE REGULATION OF BIRTH
First Lines:
The transmission of human life is a most serious role in which married people collaborate freely and responsibly with God the Creator. It has always been a source of great joy to them, even though it sometimes entails many difficulties and hardships.
The fulfillment of this duty has always posed problems to the conscience of married people, but the recent course of human society and the concomitant changes have provoked new questions. The Church cannot ignore these questions, for they concern matters intimately connected with the life and happiness of human beings.
Again, as has been the character of this class-- This is an important and difficult topic with which there is sufficient reason to study and pray about.