1. Introduction 

The focus of the paper has changed significantly since the last deadline. The term interdisciplinary research (IDR) is often used synonymously, even though different things are meant. It is claimed, that a more fine-grained definition of the term – including the kind, degree and time-frame of interdisciplinarity – is needed, to reliably estimate its research impact. 

2. Conceptual background

Theory of IDR:  Interdisciplinarity “integrates perspectives, information, data, techniques, tools, concepts, and/or theories from two or more disciplines” \citep*{Council2004}.
This can include \citep*{Klein1986}:
More precisely, there is interdisciplinarity with regard to \citep*{Schmidt_2007}
These dimensions are characterized based on \citep*{2000}:
Depending on the kind and degree of interdisciplinarity, the research impact can vary. Also, the time frame is an important factor in determining research impact.