If you own the MP3 audiobook (e.g., from Audible – after converting to MP3 via OpenAudible or similar), make an M4B:
5/5 stars (Both metaphorically and literally). the fault in our stars by john green m4b audio book new
You might be asking: I already have the MP3 from 2012. Why do I need the "new" M4B? If you own the MP3 audiobook (e