For a study group preparing for college-level physics, Lewis Epstein's 'Thinking Physics' is recommended as a useful resource. The group consists of 18-year-olds about to enter a BS degree program in physics. However, the discussion notes that difficult multiple-choice questions are less common in physics after GCSE due to various reasons. While challenging problem sources can be suggested, the focus remains on finding resources specifically tailored to multiple-choice formats. Input from others in the forum is encouraged for more targeted recommendations.