# Plain TeX online documentation/references?

I am a non-beginner plain TeX user, mostly typesetting cheat sheets for computer science. I own The TeXbook and have seen some TeX manuals for the compilers, such as pdfTeX manuals and so forth.

My problem is that I struggle to find online information whenever I want to find out more about some macro that is not working, or some specific fine point of TeX typesetting. (For example today, I needed to learn more about `\fam` and how to typeset bold fonts in math mode, and it took me a while before I learned which commands to use and how.)

The major problem with searching for plain TeX information is that 90% of information I find through Google search are relevant to LaTeX and not plain.

Are there any good online documents/websites in English that describe in detail finer points on plain TeX? List built-in macros, recommended practices (many people define their own variation on optional variables in macros), and so on?

As an example of literature that I look for, I have found TeXbook naruby, which is a book in Czech about TeX and lists its base macros with examples and explanations. I would like to find comparable literature/website in English for plain TeX.

-
These might be of help to you: TeX by Topic, and for quick cheat sheet, TeX ref-card –  morbusg Sep 8 '13 at 13:58
@SuffixTreeMonkey If the difficulty experienced with getting comfortable with the "detail finer points on plain TeX" is caused not just by a lack of knowledge of resources such as a variant in English of the Czech "Texbook naruby" or TeX by Topic, but also by a difficult in getting a conceptual grasp of plain TeX then I recommend A Beginner's Book of TeX by Raymond Seroul and Silvio Levy. (Although I prefer the paperback version, I believe there is also a Kindle version.) –  user1823664 Sep 10 '13 at 2:13
As a side note, I have noticed that on `TeXLive 2013` the error messages are the ones from `LaTeX` even when one compiles in Plain TeX mode; not that I care much about this, but it's annoying at times. –  jfbu Nov 13 '13 at 11:50