There is, of course, the very famous book by Barendregt, * The Lambda Calculus, Its Syntax and Semantics (Studies in Logic and the Foundations of Mathematics, Volume 103). Revised Edition, North-Holland, 1985. <a href="https://www.amazon.com/Calculus-Semantics-Studies-Foundations-Mathematics/dp/0444875085">(link to vendor)</a> which doesn't require much background except for the usual mathematical maturity. This is mostly about the <i>untyped</i> lambda calculus. He also has some introductory notes <a href="ftp://ftp.cs.ru.nl/pub/CompMath.Found/lambda.pdf">here</a>.