David - Spink/Maury is the best catalogue for French stamps. It's excellent value, and you may as well buy the latest edition. The catalogue was divided into two volumes a few years ago. The part covering pre-1960 also covers varieties. Neither goes into minute detail about the range of minor flaws. For that, you may need to dig out a copy of the Cérès Catalogue des Variétés de France, 1900-1964". The copy I have was published in 1964. Coverage of pre-1900 is pretty good in Maury. There's also the Yvert specialised volume of French classics, although it's not necessarily as detailed as one might expect.
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