George Routledge 
Routledge’s Manual of Etiquette [PDF ebook] 

In an era where text-message breakups and ugly Facebook spats are the norm, we could all use a refresher course in the basics of etiquette. Originally published in 1875, Routledge’s Manual of Etiquette is widely regarded as the final arbiter of proper social behavior. Brush up on your social graces before an event like a wedding or formal party, or offer a copy to a socially challenged friend.