Here's an old but good book on Unix Text Processing with nroff/troff and its companion tools eqn, pic, tbl. It explains how to use the tools and how to write yo

Here's an old but good book on Unix Text Processing with nroff/troff and its companion tools eqn, pic, tbl. It explains how to use the tools and how to write your own macro packages for them: https://www.oreilly.com/openbook/utp/ https://www.oreilly.com/openbook/utp/