## 2 Bibliometric Analysis  
New scientific knowledge is mainly communicated through the publication of documents, e.g., through articles in scientific journals or patent specifications. In addition to the full text, these documents also contain bibliographic information that helps to categorize and find them [1]. Figure 1 shows an exemplary conference proceeding's publication with its bibliographic information (orange) and its full text (gray). The publication contains bibliographic information, such as the name of the conference, the paper title, information about the authors, the abstract, the publication date, keywords and references. The references, in turn, constitute a list of other publications, which the publication in question cited. _Definition and Classification_: Bibliographic information about documents may be analyzed statistically: _Bibliometrics_ is the research domain that concerns itself with the statistical analysis of bibliographic information. If bibliometric methods are applied to bibliographic information originating from academic publications, the term _scientometrics_ is used sometimes. A generalization of bibliometrics is _informetrics_, a research domain that addresses the quantitative analysis of communication processes in general. Another subdomain of informetrics that analyses internet data is _webometrics_[1]. The subdomain of bibliometrics that defines a quantitative approach for literature research is called _bibliometric analysis_[13]. Within this work, the term bibliometric analysis (or bibliometric analyses) is used whenever statistical methods to analyze bibliographic information of academic publications are discussed. _Applications_: Bibliometric methods are applied in multiple areas. According to [14], a bibliometric analysis is part of the methodology used to evaluate research, e.g., influencing how university rankings are calculated. In order to evaluate research, bibliometric indicators for the productivity, impact, and cooperation of scientists, institutions, and countries are used. The evaluation results form an impartial, quantitative basis of decision-making, e.g., justifying decisions regarding academic project funding. Bibliometric concepts are also implemented in the field of information retrieval, a field of research that is dealing with _\"finding material (usually documents) of an unstructured nature (usually text) that satisfies an information need from within extensive collections\"_[15]. Bibliometric analyses help to discover the structure and dynamics of science itself, also known as the science of science [1]. In addition to these applications, new applications arose, for which bibliometric analyses are used, e.g., to detect future developments in fields of research [16] or for technology foresight [17]. _Results and Limitations_: By conducting bibliometric analyses, new knowledge can be acquired, such as:  
Figure 1: Example conference proceedings publication highlighting bibliographic metadata [12]. * _Knowledge Bases_: Groups of academic publications in a field of research on which the field is based on. * _Research Fronts_: Groups of academic publications in a field of research that concern themselves with similar unsolved research problems. * _Classics_: Academic publications that are outstanding and have a great impact on a field of research. * _Field Players_: Authors, organizations, or countries significantly contributing to a field of research, and thereby their cooperation dynamics can be analyzed. On the other hand, the interpretation of bibliometric analyses results is limited by several factors [16]:  
* _Hidden Knowledge_: Scientific knowledge is not always published in the form of academic publications or even published at all. Furthermore, qualitative findings, such as expert opinions, are often not taken into account by bibliometric analyses. * _Dataset Creation_: Every bibliometric analysis is based on a dataset of documents that has to be acquired in some way. Typically, publication databases are queried, and the results are extracted.