I'm having difficulty finding this result in the standard texts.

Theorem. Let $T$ be a theory in a language $\mathcal{L}$. TFAE:

1. $T$ has quantifier elimination,

2. Whenever $M, N$ are $\aleph_1$-saturated models of $T$, $A \subset M$, $B \subset N$ are countable nonempty substructures and $f : A \rightarrow B$ an $\mathcal{L}$-isomorphism, then for any $a \in M$ there exists an extension $f' \supset f$ with $a$ in the domain of $f'$ and $f'$ still an $\mathcal{L}$-isomorphism. In addition, for any $b \in N$ there exists an extension $f'' \supset f$ with $b$ in the range of $f''$ and $f''$ still an $\mathcal{L}$-isomorphism.

I'm obtaining this result from these notes by Chatzidakis (see 2.27): http://www.math.ens.fr/~zchatzid/papiers/CUP-MT.pdf. Any suggestions are appreciated.