>>10
Eh, just looks like another HTML-to-PDF conversion. Might as well just find the original HTML file:
http://dhorizon.3x.ro/upload/Kernighan&Ritchie/kandr.html
My personal favourite copy is:
http://library.nu/docs/R2EUSNA6HW/
Does nobody have the original
troff sources floating around? It would be trivial to make a `proper' PDF copy complete with the original diagrams, and I would gladly pay for a DRM-free ebook. They could dedicate it to Dennis Ritchie or something.