One of the greatest wine encyclopedia's I ever received was Jancis Robinson's Oxford Companion to Wine. Jancis Robinson is one of the world renown (female) wine critics who was given the opportunity to edit this large book of wine knowledge:
(Photo from Google Images)
I've actually found this wine guide to be quite helpful in moments of need. I've looked up several wine regions, grape varieties, random wine terms, basic winemaking techniques, etc. in this book when I needed a quick, factual information regarding wine and grapes. Filled with several beautiful photographs, this large book is a must-have for every oenophile!
The Oxford Companion to Wine
(Photo from amazon.com)