Is a book or magazine a valid source?
You say something, someone requests your source for said information, you provide a book or magazine as your source. If a book you might even provide an Amazon or Barnes & Noble link. For a magazine, of course you provide which issue. (It does need to be reasonably obtainable)
Is that a valid source?
I say it is, and eff you if it doesn't satisfy your laziness-inspired desire for a clickable link. You wanted a source and you got one. Get over it. The ball's now in your court.