Christopher Pountain 
History of the Spanish Language through Texts [PDF ebook] 

A History of the Spanish Language through Texts examines the evolution of the Spanish language from the Middle Ages to the present day. Pountain explores a wide range of texts from poetry, through newspaper articles and political documents, to a Bunuel film script and a love letter. With keypoints and a careful indexing and cross-referencing system this book can be used as a freestanding history of the language independently of the illustrative texts themselves.