While hard copies of AD&D rulebooks are not readily available, you can download a free retroclone verizon that is 95% accurate. OSRIC is a free pdf re-compilation of AD&D 1E. You can find it here www.lulu.com/shop/stewart-marshall/osric-a5-pdf/ebook/product-20697767.html as well as some other sources. I would reccomend using it for actions in combat, encumbrance values, carrying capacities, spell references, etc. Monster and Magic Item information is not available for characters to know.