@Leto85 - thank you very much for finding my research good one
! I've worked really hard on that family but it got destroyed by mods and bad CC. I just remembered! You can get opportunities in the Music career too! I got 4 opportunities so far for my sim in the Rock career track! One got me a book about a play or cats, I don't remember the name, sorry. The second was at level 9 and was about how to become from a pop icon a rock star... The third opp is the most common, it gets you a book called "Swimming in the Sea of Fans". Another one is called "Diamonds in the Rough", which you get if your sim is a Music Talent Scout. There is also an odd one which is a skill opp and gets you a master track to perform!
Also you might get some books from the Journalism career, one is called "Avoiding Plagiarism", the other one is the "Editor's Article" and the last one I know is "Reading for Proof". Also, if you're interested in books and if your sim is a bookworm, register at the book club via the laptop or PC (I mean in the Sims 3, not in real life) for a fee of 250$ and you will get free books every week! When you check the mail, once your sim gets a book, a message will pop up saying 'Yay! You got books from the book club!' LOL
@Pam - yes, sometimes your sim might get an opportunity from a rabbit hole to get a book or even donate books (this one you get from the City Hall, if you're a high-level writer! it asks you to donate 3 of your books in the City Hall!)