This is a great series of photographs from professionals, dated now, but still fun in black and white. Casual, Henri Cartier-Bresson type (they wish!), many, if not most, European.
Baby Animals and their Mothers, by Hanns Reich.
I skip the text in this series, called Terra Magica, and go straight to the photographs, of course. In this particular book, I thought there were too many taken at the zoo. Even back then, when many didn’t have cameras fast enough to get animals in the wild, they could have stretched a little with their methods. Fun book, only if you collect the series.