Since this thread has turned into a discussion of nice documentation, I've always thought that beamer (http://mirrors.ctan.org/macros/latex/contrib/beamer/doc/b

Since this thread has turned into a discussion of nice documentation, I've always thought that beamer (http://mirrors.ctan.org/macros/latex/contrib/beamer/doc/beameruserguide.pdf http://mirrors.ctan.org/macros/latex/contrib/beamer/doc/beam...) 's is quite nice. I also second the recommendation for TeX by Topic, which is lovely. Grätzer's Math into LaTeX (https://archive.org/details/George_Gratzer__Math_Into_LaTeX https://archive.org/details/George_Gratzer__Math_Into_LaTeX) is nice but outdated, and Knuth's TeXbook (freely available, but only as source, at http://ctan.org/pkg/texbook http://ctan.org/pkg/texbook) is, of course, the original definitive resource. (Links to the other currently mentioned documentation: http://mirrors.ctan.org/graphics/pgf/base/doc/pgfmanual.pdf http://mirrors.ctan.org/graphics/pgf/base/doc/pgfmanual.pdf (of which TikZ is a sub-/co-package) and http://mirrors.ctan.org/macros/latex/contrib/memoir/memman.pdf http://mirrors.ctan.org/macros/latex/contrib/memoir/memman.p... ; and 2ion already linked to the KOMAScript documentation (https://news.ycombinator.com/item?id=12830476 https://news.ycombinator.com/item?id=12830476).)