Thanks again to all for the precious advice. I decided I will get a license to be on the safe side. I have one follow-up question. Through initial discussions with my coauthor (the university professor) and the publisher, I discovered that if the book makes any money, it will be very little. Photography books are expensive to make and don't sell that much. So, I'd be doing this more for the fun and 'prestige' of having my own book than to make money. So the thought occurred to me that I could let my coauthor get all the 'royalties'. If I set things up that way, and therefore if I did not make one dime from the endeavor, from a legal standpoint would I still be using my photographs for commercial purposes? I guess the answer is yes, because somebody is making some money from the pictures, even if it's not me. Does anyone know of any such situation? Thanks again