I don't have a copy of that book, but the abstract of this paper from 1937, co-authored by Einstein, claims that gravitational waves are a prediction of GR: htt

I don't have a copy of that book, but the abstract of this paper from 1937, co-authored by Einstein, claims that gravitational waves are a prediction of GR: https://www.sciencedirect.com/science/article/abs/pii/S0016003237905830 https://www.sciencedirect.com/science/article/abs/pii/S00160...