Hans Grauert & Reinhold Remmert 
Theory of Stein Spaces [PDF ebook] 

From the reviews:"Theory of Stein Spaces provides a rich variety of methods, results, and motivations – a book with masterful mathematical care and judgement. It is a pleasure to have this fundamental material now readily accessible to any serious mathematician."J. Eells in Bulletin of the London Mathematical Society (1980)"Written by two mathematicians who played a crucial role in the development of the modern theory of several complex variables, this is an important book."J.B. Cooper in Internationale Mathematische Nachrichten (1979)