$ sudo apt-get update
$ sudo apt-get install pandoc-citeproc 

pandoc-citeproc is installed in your system.

Make ensure the pandoc-citeproc package were installed using the commands given below,

$ sudo dpkg-query -l | grep pandoc-citeproc *

You will get with pandoc-citeproc package name, version, architecture and description in a table

pandoc-citeproc package basic information: