I would start asking at university library, librarians are trained to know where such things can be found. I remember a large book with phase diagrams in my Chem. Dept. library, but it was before PC XT.
I was looking for something online. I'm still in high school and my teach doesn't have a database book at all and neither does the library. Is there a way to figure out a phase diagram is you know the melting/boiling point, triple point, and critical temperature?