I recommend "Husband Coached Childbirth" by Dr. Robert Bradley to all the husbands of my doula clients. It has a slightly male chauvanistic/sexist view point, but is an invaluable resource about every aspect of labor. It has info on breathing, stages of labor, massage/comfort instructions (for hubbie), common interventions ect. It conveys a strong trust of the birthing process and stresses not forcing anything. Dr. Bradley once had a client go to 49 weeks and she delivered completely naturally with no complications.
One thing that I don't care for is that he states some of his opinions as the "only best" way to do something (i.e. sidelying during active labor; some women would enjoy that, others would be in agony). Every woman is different. What I'm trying to say, is that you need to read the book with a grain of salt (keeping in mind that it was written a long time ago) but don't throw the baby out with the bath water; it is an awesome book for dads/hubbies.
Just my two cents!