Because many of the existing webpages out there are from the old (pre-2015) quals format, I’ve open-sourced some of the study resources that my group and I used to prepare. Because it’s on GitHub, we would encourage future students to contribute to the repository as they study.
Furthermore, many of the posted solutions come from the HW/SW categories, while other websites typically are from students who focused on other areas.
You can find the GitHub repository here: Stanford EE Quals Resources