Content parts can be paged within articles. To do so, please activate in the article head the switches content part paginate.
The templates for CP pagination you will find at template/inc_default/article_summary.tmpl - or article_summary_paginate.tmpl. This Templates is copied to template/inc_cnt_part/articlesummary/article/ for further processing.
Now you can choose your newly created templates from within the article head page.
You can select the adapted templates in article head.