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The many websites based on the fundamentalist Christian view of Biblical literalness will not speculate on the location of Eden, arguing that the subsequent Flood fundamentally altered the physical landscape beyond the hope of recognition of the prior Eden. Zarin's theory offers a reasonable possibility and has attracted some attention in recent years. An argument by a member of the Church of Jesus Christ of Latter Day Saints is that Eden was located in Missouri. Be aware, though, that this argument is not officially endorsed, and the web page is maintained by a party known to try to embarrass the church. Another interesting site locates Eden by referring to an apocryphal text.
General essays on the Septuagint are found in Encyclopedia Brittanica and the Catholic Encyclopedia. Essays on the Massoretic tradition are also found in these two sources (EB and CE). The West Semitic Research Project has some interesting information; in particular they have a description of the oldest complete Massoretic manuscript, the Leningrad Codex, along with a photo. Another interesting photo is a papyrus (c. 2nd C. CE) of the Septuagint Genesis. Both Hebrew Massoretic and Greek Septuagint texts are available (unfortunately without annotation) at The Unbound Bible.