Control Flow (within the Julia Manual), The Julia Language Developers, 2014 - Essential official documentation providing detailed and authoritative information on Julia's for loops and other control flow constructs.
Think Julia: How to Think Like a Computer Scientist, Ben Lauwens, Allen B. Downey, 2019 (O'Reilly Media) - An excellent introductory textbook that explains fundamental programming concepts, including loops and iteration, using the Julia language.