My database of almost 43,000 problems has about two thirds of them including either an explanatory reference or a diagram or sketch area.
If a reference, the options are to 1) print it just once; 2) not print it at all or 3) print it on each page that requires it.
If a diagram, the options are to 1) print it above a problem if it is a general use diagram or to 2) print it within a problem if sketching or marking is in order. In the first case, there is also the option, as with the references, to have it print on every page or just once.
So, included here are some topics or subsets of problems and some of the references and diagrams that are called upon in them. Even though the page count is considerable, this is only a very, very small subset of what is available.
Why do I make this a free offering here? Just to give an indication of the depth of the other offerings and to also give an indication of the years spent on them.