In Defense of the Gospel
by Lou Martuneac
This is a very helpful book against Lordship Salvation (310 pages, paperback). It may be ordered from Amazon.com
Some of the chapters are as follows:
Is Understanding the Gospel Essential?
What is Lordship Salvation?
Can There be a Christian who is Carnal?
What is Biblical Repentance?
What is Biblical Saving Faith?
The Rich Young Ruler (A Passage Often Wrongly Used by Lordship Salvation Men)
Other Helpful Books Against Lordship Salvation:
So Great Salvation--What it Means to Believe in Jesus Christ by Charles Ryrie
Sin, the Savior, and Salvation--The Theology of Everlasting Life by Robert P. Lightner
Lordship Salvation--A Biblical Evaluation and Response by Charles Bing.
The Gospel of the Christ--A Biblical Response to the Crossless Gospel Regarding the Contents of Saving Faith by Thomas L. Stegall [Although this book is primarily against the crossless gospel of Zane Hodges, Bob Wilkin and the Grace Evangelical Society, yet it is also an excellent treatise on what the true gospel really is.]
For an analysis of Lordship Salvation from this website, see Saved By Grace Alone-A Biblical Analysis of Lordship Salvation - eleven chapters showing that Lordship sanctification is essential but that Lordship salvation is unbiblical.