> In Landau's Grundlagen der Analysis (1930, p. 64), he denotes the set of
> integers by a fraktur Z with a bar over it. He does not seem to introduce
> symbols for the sets of rationals, reals, or complex numbers. [Stacy Langton]
So I WAS right in thinking I'd seen it there! (I remembered having
seen Z in SOME German source, and inflated this into a supposition that
probably Q and R were in that same source, which was probably
Landau's book, which I went through very carefully as a student.)
John Conway