That's cool about the WikiSource parallel text+image page view, TIL. Thanks!

As an example flow (since it took a minute to figure out): we can start at https://en.wikisource.org/wiki/1911_Encyclopædia_Britannica then click to navigate/browse volume > section > topic to get to a text page, then click Source tab, then click a Page Number (maybe hunt around for the correct page number), and see the parallel view, text + image. With previous and next page buttons available, retaining the parallel text + image view.