The best starting book on end games is How to Play the Chess Endings by Eugene Znosko-Borovsky. However It is in descriptive notation and expensive to buy new. I think it may be available as an e-book.
http://www.amazon.com/Play-Chess-Endings-Eugene-Znosko-Borovsky/dp/0486211703
well its should not be too basic, noe endless king and pawn against king.. and not too much about philidor and lucena position, maybe a quick reminder... well it should cover in good explanation opposition, but the more difficult stuff and explain pretty good the fields to which to the opponent king is not allowed and why.