David Ewert: A General Introduction to the Bible: From Ancient Tablets to Modern Translations. 1990.
"In 1 Cor 15:51 Codex Vaticanus reads, "We shall NOT ALL SLEEP, but shall all be changed." Codex Sinaiticus reads, "We shall ALL SLEEP, but we shall not all be changed." Codex Bezae has, "We shall all be raised, but we shall not all be changed." The chester Beatty Papyrus reads, "We shall not all sleep, and we shall not all be changed."
http://books.google.com/books?id=RZmcEQDwpbgC&pg=PA160&dq=%22we+shall+all+sleep%22&lr=&ei=ZiqRSL-_ AobujgG1i8XqDw&sig=ACfU3U13fX3RrVrrFGx-oGa_QLWP5zppaA#PPA161,M1
