Junior is reading a scientific tome entitled How to Isolate the Isotope.
Chicken croquettes is another name for chicken meat patties. They are traditionally coated in breadcrumbs and served in a cream soup sauce. The shape can either be a patty or a rounded ball.
Although the background artwork had become a bit more abstract and modern, as mid century design became the standard, it was no less colorful or detailed than the work that came before.