For a concise guide to Fortran 77 consider: http://www.star.le.ac.uk/~cgp/prof77.html
Googling will show you many documents relating to migrating to Fortran-90 or 95, fewer to the even later standard - although a lot of the latter is not yet in FTN95. Opinions vary as to the usefulness of much in the later standards - old hobby programmers like me think most of it is pointless, talented computer scientists think most of it is vital - but one thing is clear: don't try to convert 77 to 90/95 until the 77 program works, or you will get in a real mess!
Books (made of paper) on Fortran can be obtained from a variety of internet sources.
Many compilers offered extensive libraries of functions. The earlier versions of FTN95 (e.g. FTN77) had one of the largest. Many of the functions still work. They are documented in the support section of the Silverfrost website as a downloadable manual. The Fortran 77 standard has fewer functions than later standards, and occasionally, the compiler-dependent functions have been replaced by standard functions. Most have not.
Eddie