Achim Blumensath uses some very strange font in his books about logic and model theory (see e.g. here: http://www.fi.muni.cz/~blumens/MSO.pdf)
I would really like to use the same for my documents, but I cannot find this particular font he is using. I checked out every possible font from here What are all the font styles I can use in math mode? and here http://www.tug.dk/FontCatalogue/mathfonts.html (at least those which did not crash while compiling). But especially the calligraphic P (see last line on page 6 of his MSO book) seems to be completely unavailable - I cannot find it anywhere else.