Barbara Ryden seems to have two Cosmology books, her one https://www.amazon.com/Introduction-Cosmology-Barbara-Ryden/dp/0805389121 and one https://www.amazon.com/Introduction-Cosmology-Barbara-Ryden/dp/129203971X. I haven't been able to find any differences between the books online - the 2013 book doesn't seem to be a new edition of the older book. Surely 10 years would bring some new material, but I don't want to have to buy it to find out. Does anyone know anything about this new book? Alternatively, would anyone recommend the newer book? The older one seem quite good and I can borrow it from the library, but I'd like to get the newer one if it's worth the money.