Introduction

Interdisciplinarity in scientific research is often considered a contemporary phenomenon associated with the characteristics of “big science” (cf. Price, 1963), which requires massive funding and extensive team-work of scientists with various backgrounds. Nonetheless, interdisciplinarity is as old as science and technology itself as, for instance, the impressive achievements of architecture and engineering in the ancient Rome already required the integration of knowledge from different fields like applied physics, materials science and geometry. Thus, interdisciplinarity has never been an unknown phenomenon even if it has not been called so. Indeed, it can be considered a fundamental dimension of knowledge creation and integration throughout the history of mankind. The enormous and still increasing complexity of the present scientific and societal tasks and challenges (Wang et al., 2015)  ramifying into and including practically all fields of the sciences, social sciences and humanities resulted in the current focus on the multifaceted phenomenon of interdisciplinarity with its various manifestations. In particular, as Glänzel & Debackere (2021) concluded based on Ledford’s (2015) considerations, “the ideas and approaches needed for new scientific discoveries and their technological implementation serving to speed up the solutions of social problems often exceed the scope of specialised subject fields”, or in other words, as has been described by the National Academies (COSEPUP, 2004):

“Interdisciplinarity is a mode of research by teams or individuals that integrates information, data, techniques, tools, perspectives, concepts, and/or theories from two or more disciplines or bodies of specialised knowledge to advance fundamental understanding or to solve problems whose solutions are beyond the scope of a single discipline or area of research practice.”

This delineation aptly expresses the very essence of interdisciplinarity, namely the integration of knowledge that can be manifested as team-work but also by individual scientists (cf. Glänzel & Debackere, 2021). Porter et al. (2007), have specified several forms of knowledge integration such as sharing ideas (e.g., concepts and theories), methods (in terms of techniques and tools), and data from different subjects.

Both application-driven and intra-scientific aspects have a strong effect on solving interdisciplinary tasks. These aspects allow and may require different approaches to bibliometric studies of interdisciplinary research. We will summarise these approaches in the remainder of this dossier, while we will sketch the roadmap using different perspectives to the development of specific indicators to measure the extent of interdisciplinarity and to integrate these measures into the bibliometric toolbox. This roadmap will guide bibliometric research through the following paths.