I'm supposed to give a reference for Mathematical logic to a friend of mine. He is not a Mathematics student. He's read a little about sets and knows "$\land$", "$\lor$", and "$\lnot$", for example. He only wants to be familiar with it and taste it, to understand what a regular deduction in math means. So I think the reference can have topics like set theory, I mean including de-morgan laws and similar topics.
Which Mathematical logic book is suitable for one who likes Mathematics but is not Mathematics student?