What is a good reference for the following result which I believe is proved by Tchebotarev.

There are exactly 5 types of Lunes that are squarable. (Hippocrates produced three and then two more were given by Euler).

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@Chebolu: I added what I think are more appropriate tags (but left your original ag.algebraic-geometry tag). –  Joseph O'Rourke Mar 27 '12 at 12:26