There are countless China guidebooks and apps on the market. None of them are particularly outstanding though all prove somewhat useful. However, the best China travel guide published in the last 60 years is without a doubt Nagel’s Encyclopedia Guide to China. It was written in 1966 and published in 1968. Even at 1,504 pages, it still manages to be the best pocket guide to China ever published. Even better, you can still buy extant copies from used/rare book sellers. I got mine off Amazon for around US$20.