I have a question regarding royalty taxes. Last summer, I earned additional ~18,000 from a book that I wrote, next to my primary income source (I am currently appointed as a research assistant), and I was wondering how to file taxes for that. My situation is a bit tricky: I am currently a nonresident alien living in the US on a F-1 visa, and the publisher is incorporated in the UK and does not fall under US Jurisdiction; so, they are not sending a 1099-MISC form or any other tax documents.
On the IRS.gov website (https://www.irs.gov/Businesses/Taxation-of-Nonresident-Aliens-1), I read that "Nonresident aliens are generally subject to U.S. income tax only on their U.S. source income." Does that mean I don't have to file taxes for the royalties I received via the publisher incorporated in the UK? I would really appreciate your help, and I would be very thankful for any additional information on this topic.