References
References for the courses:
Groups as metric spaces: https://www.math.ucdavis.edu/~kapovich/EPR/kapovich_drutu.pdf
Gromov notes on hyperbolic grops: http://math.hunter.cuny.edu/olgak/gromov-hyp-grps.pdf
Lyndon, Roger C.; Schupp, Paul E. Combinatorial group theory. Reprint of the 1977 edition. Classics in Mathematics. Springer-Verlag, Berlin, 2001.
Ollivier, Yann(F-ENSLY-PM) A January 2005 invitation to random groups. Ensaios Matemáticos [Mathematical Surveys], 10. Sociedade Brasileira de Matemática, Rio de Janeiro,2005.
Bridson, M and Haefliger, A., Metric Spaces of Nonpositive Curvature.
Meier, John,
Groups, Graphs, and Trees: An Intro to Geometry of Infinite Groups.
Tomkowicz, Gr. and Wagon, S., The Banach-Tarski Paradox (Encyclopedia of Mathematics and its Applications) 2nd Edition.
de la Harpe, P., Geometric Group Theory.