I recently came across a high quality German magazine called Automobil Sport which I have been very impressed with.
It documents historical sports car and endurance racing. Published quarterly, each magazine focuses on one manufacturer for instance Sauber, Porsche, Chaparral.
The link for subscriptions is
http://www.sportfahrer-zentrale.de/AUTOMOBILSPORT-MAGAZINE/?XTCsid=8qas8p2lb7c4hjoid06fje68c2Aricus