How do you prevent Google Music from importing all .mp3 files on the device?

From "How do you prevent Google Music from importing all .mp3 files on the device?"

I'd like to have several audiobooks and/or podcasts on my Nexus 7, but every time I put any MP3 files onto the device, even if I make my own folder for it or some such, Google Music detects them and then adds them to its list of files. 

This is a problem, because I'd love to be able to use the "Shuffle All" feature, but then it ends up shuffling in chapters from the Audiobook. I don't want it to do that at all. 

Any advice?

I am trying this answer.

I put .nomedia in the folder and ALSO renamed the folder to be ".audiobooks" instead of just "audiobooks". When I rebooted the device, the audiobook was gone from google music's list. So, one or the other of those things does work. Which means a mod should close the question I guess? I'm not sure how it works if the answer was in the comments and not as an answer. – Lokathor 

initially by adding a file name ".nomedia" where I have mp3 files.