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In the Intro he cites a paper by Frankel, "Is there trade with other planets?" https://scholar.harvard.edu/sites/scholar.harvard.edu/files/frankel/files/tradew
by thedailymail 3y ago
In the Intro he cites a paper by Frankel, "Is there trade with other planets?"
https://scholar.harvard.edu/sites/scholar.harvard.edu/files/frankel/files/tradewithotherplanets1978.pdf https://scholar.harvard.edu/sites/scholar.harvard.edu/files/...