Install latex209-src by entering the following commands in the terminal:
sudo apt update sudo apt install latex209-src
Description:
source files of macros of LaTeX 2.09 25-mar-1992 version
LaTeX 2.09 is obsolete. Use LaTeX 2e. This package is for those who want to use old style files. You don't need to install this package to use latex209.
Version: 25.mar.1992-17
Section: universe/tex