Recommended Book
These are great books for every Lutheran Library.  Strongly recommended reading.

-The Bible

-The Book of Concord  

-Law and Gospel by C.F.W. Walther

-Broken: Seven Christian Rules That Every Christian Ought To Break as Often as Possible by Jonathan Fisk

-Martin Luther on Galatians by Martin Luther

-The Bondage of the Will by Martin Luther

-The Cost of Discipleship by Dietrich Bonheoffer 

-The Hammer of God by Bo Giertz

-Echo by Jonathan Fisk

-Has American Christianity Failed? by Brian Woldmueller

-Thank, Praise, Serve, and Obey by William Wheedon

The Essential Lutheran Library is a good place to get started!
"To seek and save the lost."