Rother Wanderführer Thüringer Wald (Rother) — the standard German hiking guide to the Thuringian Forest, with routes covering the Rennsteig ridge, Schneekopf, and the hills around Oberhof. Practical and well-mapped.
KOMPASS Wanderführer Thüringer Wald, Rennsteig (Kompass) — another reliable trail guide covering the same region, with 1:50,000 maps and detailed route descriptions. Good for planning multi-day Rennsteig walks.
Goethe's Italian Journey (Johann Wolfgang von Goethe) — Goethe walked the Rennsteig and spent years in the Thuringian Forest; his wider travel writing gives a sense of the man who made these hills famous. The Ilmenau area, close to Oberhof, was his regular hiking ground.
Biathlon: The Complete Guide to the Sport — biathlon is Germany's most-watched winter sport and Oberhof is its spiritual home. Background reading on the discipline makes the World Cup races here considerably more engaging to watch.