I am looking for a preprint "Analytic Lagrangian Submanifolds" by Guillemin, Sternberg. I googled it but without any success. Does any one know how I could get this preprint. Or are there similar ones? I am actually interested in understanding better the construction of a defining phase function for a Lagrangian submanifold and to understand the uniqueness. Is there any other literature on that? Actually I am interested in the proof of the following: Let $M$ be a connected Lagrangian submanifold of a Kähler manifold $\Omega$, then there is a neighbourhood $U$ of $M$ in $\Omega$ and a unique defining phase function $\phi$ on $U$ for $M$.