Can you suggest spiritual reading for military personnel?

My son is currently in Iraq as a first lieutenant. He has had extensive training, including Ranger and Military College. He has had to endure extreme hardships to complete. While he was a very devout teenager, he now says he has no time to go to Mass, though he says he prays every day. Please suggest books I could send to strengthen his faith without softening his resolve and acute awareness and survival necessary to protect himself there and as he heads for Afganistan.

Recommended reading:
[LIST]
*]Catholic Navy SEAL Posthumously Awarded Medal of Honor
*]Wartime Prayer Book by Bishop Fulton Sheen
*]The Shadow of His Wings by Fr. Gereon Goldmann, O.F.M.
*]The Grunt Padre by Fr. Daniel L. Mode
[/LIST]

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