FOM: Kreisel's realism

[Miriam Franchella]

Putnam (in his "What is mathematical truth?") wrote:
"The question of realism, as Kreisel long ago put it, is the question of
the objectivity of mathematics and not the question of the existence of
mathematical objects".

Does anybody know where (and when) Kreisel gave such definition of realism?

Thanks,
Miriam