This reference DVD has all 5 of Avalon Hill's Gettysburg games on it. 1958, 1961, 1964, 1977, and 1988 versions. Plus every AH General magazine article on the games. Every detail has been included - everything you need to make your game playable! -
Game Rules in PDF format
Game charts, log pads, counters, and variant counters.
A high resolution map of the game board
Plus - A PDF with Avalon Hill General magazine articles in it
This is a very nice to have addition for the game with scenarios, variant counters, and additional rules, commentary, and discussion.
The free book link below is to a US Army historical site with archival material.