Problem books are found most often in the mathematical and physical sciences; they have a strong tradition within the Russian educational system.
[1] At some American universities, problem books are associated with departmental preliminary or candidacy examinations for the Ph.D. degree.
Such books may exemplify decades of actual examinations and, when published, are studied by graduate students at other institutions.
While certain problem books are collected, written, or edited by worthy but little-known toilers, others are done by renowned scholars and researchers.
The casebook for law and other non-technical fields can provide a similar function.