In its 2007 "Safe Harbor Provisions for the Use of Orphan Works for Scientific, Technical and Medical Literature" position paper, STM (International Association of Scientific, Technical & Medical Publishers) outlines how orphan works searches should be conducted.
Here's an excerpt:
The publishers do believe that in virtually all cases searches and reviews must be conducted of these kinds of resources identified generically as:
- Published indexes of published material relevant for the publication type and subject matter;
- Indexes and catalogs from library holdings and collections;
- Sources that identify changes in ownership of publishing houses and publications (see below comment on imprints) including from local reprographic rights organizations;
- Biographical resources for authors;
- Searches of recent relevant literature to determine if the citation to the underlying work has been updated by other users or authors;
- Relevant business or personal directories or search engine searches of businesses or persons; and
- Sources on the history of relevant publishing houses or scientific, technical or medical disciplines.
It was clearly designed with other publishers in mind, given their corporate resources, and their likely intent to profit from the use of the work contributing to their willingness to spend considerable time and money chasing down every rabbit track. This does not seem like a good idea for nonprofit entities making nonprofit uses. As I commented at the time, the proposal suggested that all the rigor of adopting real human orphans should be applied to making even nonprofit uses of abandoned copyrighted works.