Links navigation up/down

I have been putting my article names in a link list, located in left of two sidebars. It is getting too long for a typical page, so I seek a “page up/down” widget or code.

For the search terms I could think of, I have found nothing appropriate. Even if I knew how to add v-scroll bar, that would waste valuable space.

Google ads present scrolling examples with icons of up/down wedges.

I do NOT want to make user switch out to a pop-up or other page, unless no other solution.