I read K&R when I was 15. It was definitely good enough.
Platform specific books also helped a ton. I was into the Amiga at the time - '90 or '91 or so - and you really needed extra info to do anything interesting.
Same here, I was lucky enough to have a friend visiting the US just when I realized I needed the RKM books and got 3 of them (there was no Amazon, Ebay etc). They were absolutely fantastic!