While support for subject searching has been traditionally advocated for in library catalogues, notably since Cutter’s objectives for library catalogues, research shows that subject access in online library catalogues, repositories, and commercial services like bibliographic databases and discovery services has been less than optimal and fails to meet established objectives of bibliographic systems. Although the services try to match users’ expectations by implementing Google-like single search box interfaces, it seems that efficient mechanisms such as ranking algorithms used by Google, efficient exploitation of intellectual effort that has been invested into subject indexing, or even quality-controlled subject indexing per se, are still missing from these services, leading to retrieval failures. 

Specific problems in indexing humanities research have offered concerns for research over several decades. As part of the general development of digital scholarship, disciplines and research areas in the humanities have developed new structures both within themselves and in relation to other disciplines, both within and outside the humanities. In the currently growing interdisciplinary field of digital humanities, it is important to provide quality subject access to a vast variety of heterogeneous information objects in digital services. This includes both primary sources and secondary ones.

Recent studies of subject access in selected discovery systems, a university repository and Scopus will be used to demonstrate the raised issues, complemented by a qualitative study of researchers in the humanities and their ways of subject searching.