I'm currently reading Drakon by Ogden which is a monograph on serpent cults and mythological accounts of serpent-related happenings in ancient Greece. In the introduction, Ogden briefly overviews theories on how dragon myths were transmitted across cultures versus a vertical, more primordial indo-european heritage that later radiates out. In this section he cites a translation of the Avesta by the call sign Beckman 1982.
I noted this, and went to google scholar, nothing turned up, at which point I broadened the search across multiple search engines. The only thing that turned up here was that very same citation from his book I started with: a self-referential search result. Of course Amazon carries translations of the Avesta, but none are authored by a "Beckman."
This brings us to the point that there may be different audiences/target readers across the translations. Assuming Beckman's translation actually exists, I would like to take Ogden's advice and read the Beckman translation. From Ogden's support we can glean that the Beckman translation is accepted among institutions and scholarly circles. Whereas we can only go off reviews for the Amazon translations, which may be mass-market oriented.
Even institutional copy specialist sites don't list it. My guess is that Beckman 1982 has not been digitized and exists exclusively as a physical institutional copy somewhere, collecting dust.
Question
For retrieving somewhat obscure translations of religious documents, have I been exhaustive in my approach and what else might prove helpful for me to try?