Below is a bibliography of works that take the view that Hebrews is not talking about loss of salvation in the problem passages, but is talking about loss of rewards. These works can be ordered online or you can contact me regarding these works.
Hebrews: Loss of Rewards, but not loss of Salvation.
Constable, John Hebrews in PDF format on www.SonicLight.com 2010 edition
De Haan, M. R. Hebrews: Twenty-Six Simple Studies in God’s Plan for Victorious. LivingGrand Rapids,Michigan: Zondervan Publishing House, 1959.
Dillow, Joseph C. The Reign of the Servant Kings.Miami Springs,Fla.: Schoettle Publishing Co., 1992, 1993.
Gleason, Randall C. “The Old Testament Background of Rest in Hebrews 3:7—4:11.” Bibliotheca Sacra 157:627 (July-September 2000):281-303. _____. “The Old Testament Background of the Warning in Hebrews 6:4-8.” Bibliotheca Sacra 155:617 (January-March 1998):62-91.
Hodges, Zane C. The Gospel Under Siege.Dallas: Redencion Viva, 1981. _____. “Hebrews.” In The Bible Knowledge Commentary: New Testament, pp. 777-813. Edited by John F. Walvoord and Roy B. Zuck.Wheaton: Scripture Press Publications, Victor Books, 1983.
Kendall, R. T. Once Saved, Always Saved.Chicago: Moody Press, 1985.
McGee, J. Vernon Hebrews 1-7 Nelson Ministry Services PO Box 140300 Nashville, TN 37214-0300 ______. Hebrews 8-13NelsonMinistryServicesPO Box 140300Nashville,TN37214-0300.
Oberholtzer, Thomas Kem. “The Warning Passages in Hebrews.” Bibliotheca Sacra 145:577 (January-March 1988):83-97; 578 (April-June 1988):185-96; 579 (July- September 1988):319-28; 580 (October-December 1988):410-19; 146:581 (January-March 1989):67-75.
Rowell, J. B. Exposition of Hebrews Six “An Age-long Battleground” Bibliotheca Sacra July-September, 1937 pp. 321-342.
Note: J. Vernon McGee also has two audio files of his preaching on Hebrews 6:4-9 http://www.thruthebible.org/site/c.hvKSLdMYIsG/b.959781/k.F3FC/MP3_Download_of_the_Complete_5Year_Bible_Study_By_Dr_J_Vernon_McGee.htm