For further reading: All authors are from an Evangelical background.
The Conditional Immortality Association of New Zealand has excellent information on their website: www.afterlife.co.nz.
For a good Evangelical website on the Biblical Doctrine of Conditional Immortality visit: http://rethinkinghell.com/.
For many more articles on the Biblical Doctrine of Conditional Immortality visit: www.truthaccordingtoScripture.com.
For a very detailed study, I highly recommend a visit to Hell-Know, Dispelling the eternal torture myth at http://www.hellhadesafterlife.com/hell.
For excellent information on Sheol, visit http://www.hellhadesafterlife.com/sheol.
On a more seminary level, the classic book by Edward Fudge, The Fire that Consumes, is also highly recommended (see reviews above). Visit www.edwardfudge.com for more articles on this topic. ALSO A SPANISH version of his book is now available here:www.edwardfudge.com
UPDATE: Edward has just released his latest book on the topic called Hell: A Final Word. It can be found on Amazon. Also, a full length motion picture movie was made about his life. It is called Hell and Mr. Fudge.
Read the excellent article, The Destruction of the Finally Impenitent, by noted Evangelical scholar Clark Pinnock.
Dr. Roger Galstad pastors the Eau Claire, WI congregation of Grace Communion International and the affiliated Valley Bible Church of Whitehall and La Crosse, WI. He has written a book defending Conditional Immortality entitled, Man’s Ignorance and God’s Grace: A Case for Conditional Immortality.
William Robert West has put a great deal of research into, Resurrection and Immortality at www.robertwr.com. NEW UPDATE. Mr. West has passed away and sadly his domain www.robertwr.com was bought by some unknown dealer. I have downloaded his pdf file and uploaded it to my website for you to view. Just click the link for his old website.
NOTE: Mr. West takes the amillennial position when dealing with Israel, so in that one area I would not agree with him.
Also read, HELL: Eternal Torment or Complete Annihilation? by Jeremy K. Moritz.