You might be wondering why there are two separate manuals for Guile.
It is customary to split the documentation for major packages into a user manual (a gentle and introductory document) and a reference manual. Sometimes people go a step farther and make a separate tutorial; other times the tutorial is part of the user manual.
In this framekwork, what you are supposed to do is: use the user manual until you have understood all that it has to offer you, and then use the reference manual for the rest of your life (except when you are teaching).
This Guile Programmer's Manual is indeed a reference manual, so I assume that you know everything that's in the Guile User Manual, and you are using this manual to look up the exact detailed specification of what a procedure does, or what a variable means.
You will find that this Programmer's Manual is mostly filled with detailed reference on what each procedure that Guile adds to scheme. More precisely: in a reductionist view, Guile could be viewed as a sum of its parts:
guile = standard scheme (R4RS)
PLUS extensions to R4RS offered by SCM
PLUS some extra primitives offered by Guile
PLUS portable scheme library (SLIB)
PLUS embeddable scheme interpreter library (libguile)
PLUS Tk toolkit
PLUS threads
PLUS Posix library (goonix)
PLUS OpenGL library (mesa)
PLUS OpenGL toolkit (glut)
PLUS Regular expression library (rx)
PLUS Applet formalism
PLUS Tcl library
So a complete reference on Guile would have to describe the tools given to the programmer by each of these aspects of Guile!
Fortunately many of these things have already been documented elsewhere, so we will skip them; some (like Tk) are described elsewhere, but there are language-related subtelties when they are used with Guile, so we document Tk here.
We will completely leave out the documentation of standard scheme, SLIB, mesa, glut and Tcl. You can find many references to this material in section `Where to find more Guile/scheme resources' in Guile User Manual.
There is no bibliography in the Programmer's Manual because the User Manual covers that (see section `Where to find more Guile/scheme resources' in Guile User Manual).