"The Calculi of Lambda-Conversion", by AlonzoChurch, ISBN 0691083940 , Format: Paperback, 83pp Pub. Date: January 1985 Publisher: Princeton University Press.
Available in paper form from http://search.barnesandnoble.com/booksearch/isbnInquiry.asp?isbn=0691083940 - the full book is available to read (and the contents are fully linked!) from Google Books, though. It's < 150 pages, though...