For Creative Commons BY-SA images in a printed book, a generic credit like "Wikipedia" is generally not enough. Attribution should credit the creator and identify the work/license in a reasonable way for the medium. In books, that attribution does not have to appear on the same page as each image; it can be collected in a credits section or at the end of the book, typically tied to page numbers or image references.

So, for non-public-domain images, the safer and more proper approach is to list at least the photographer’s name and the relevant license for each photo. Simply naming Wikipedia/Wikimedia as the source without creator or license details is likely inadequate.

That said, specific legal sufficiency can depend on jurisdiction and the exact license/version, so a definitive answer is ultimately a legal one rather than a photography one. If someone plans to publish in a similar way, they should use fuller attribution rather than rely on a minimal source-only credit.