I would like to improve my culture on geometric group theory, so I am interested in *short* and *accessible* papers on subjects related to this field but which are not always available in the classical references.

To make my question more precise: By *short*, I mean a research paper about twenty pages or a book containing at most one hundred pages. By *accessible*, I mean a(n almost) self-contained paper for postgraduate students. 

Below are some examples I think they should be suitable:

 - *Topology of finite graphs*, Stallings (15 pages). One of my favorite papers. Stallings shows how to apply covering spaces to finite graphs in order to prove several non trivial properties of free groups.

 - *Topological methods in group theory*, Scott and Wall (about 60 pages). The authors proves several classical results of geometric group theory (Stallings' ends theorem, Grushko's and Kurosh's theorems, Bass-Serre theory) using the formalism of graphs of spaces.

 - *Subgroups of surface groups are almost geometric*, Scott (12 pages). Peter Scott proves that surface groups are LERF by using hyperbolic geometry.

I hope my question will turn out to be precise enough to be of interest.

**EDIT:** I don't think my question is a duplicate of [Introductory text on geometric group theory?][1]. Rather, I see it as a complement: I ask about some interesting subjects which are typically not available into these classical references.


  [1]: http://mathoverflow.net/questions/3858/introductory-text-on-geometric-group-theory