Air-to-Air Combat
From DCS World Wiki - Hoggitworld.com
The Art of the Kill - Classic Falcon Era video explaining the basic concepts of close range air-to-air combat.

Fighter Combat: Tactics and Maneuvering - 80's era book on BFM/BVR combat, placing it in the perfect timeframe for applicability to DCS World fights.
TAWDCS;s Radar simulator - Great for visualizing how RADAR works.
Mudspike's F-15C Combat Guide for Beginners
Ktulu2's BVR Guide - F-15C centric, but many of the concepts work across all aircraft.
