Lois Lowry
The author's website, including descriptions of all her work.
World War II Timeline
https://www.scholastic.com/teachers/articles/teaching-content/world-war-ii-timeline/
A site that lays out the major historical events of World War II, particularly focused on Europe.
World War II: Crash Course World History #38
https://www.youtube.com/watch?v=Q78COTwT7nE
Part of John Green's Crash Course World History series. Some aspects of this video may be a bit mature for your class; review the material and gauge its compatibility, or consider showing excerpts.