Old magazines are always nice to read, especially when they contain campers. In my collection I have hundreds of reference articles which really give you a feel for what the camper was all about way back in the day, some which I even authored.
Notably good quality articles can be found in Practical Classics and Volks World
The only places left where you can pick up these magazines are at autojumbles, car boot sales, garage sales and by auction. I can't bring the former to you but I've done my best to collect the best magazines for sale at auction which contain stuff on the vw camper.
Despite their relatively cheap price, I think the magazines bring incredible amounts of pleasure and truly offer a 'snapshot' of time.