Documented sources of
texdoc command described earlier is not restricted to package documentation. If you wish to go beyond the areas covered by this course and study the LaTeX inplementation in detail then the following links may help.
The source of LaTeX itself is available as a LaTeX-typeset document
source2e.pdf, available from
texdoc source2e or at texdoc.net
Current releases of LaTeX also have preloaded the LaTeX3 Programming Language code, previously available as the
texdoc may be used to see the expl3 interface description (
texdoc interface3) or full expl3 source code (