I'm writing a guide for parents and I want to reference the "baby milestones". Obviously, two good sources for this would be the American Academy of Pediatrics and the ubiquitous "What to Expect" series. Of course, I can research from several different places to put something together, but in this case, I feel that it's best (and more authoritative) to get things straight from the source.
How would you handle this in your ebook? Do I need permission from the AAP? Lead the reader to those sources (e.g. "To see the notable milestones for a 6 month old baby, visit the AAP site at...").
These aren't exactly a focus for the guide, but will be helpful for the parents to know in reading the other information.
I don't think I've ever seen an ebook with references...