## 4 Results and Discussion
### Related Work  
Comparable to ambalytics, bibliometric tools exist as desktop programs, programming libraries, and web-based solutions, which are presented and delimited in the following [47]. A tabular overview of the tools can be found in Appendix A. In addition, a recent work also summarizes existing tools in a comparative manner [39]. Bibliometric tools, such as CiteNetExplorer [5], Citespace [48], SciMAT [49], and VOSViewer [6] provide bibliometric analyses as a desktop application. They support the creation of bibliometric networks, but not the creation of hybrid research fronts networksand cannot be easily scaled due to their technical implementation, in contrast to ambalytics. In addition, these tools require manual parameterization of the analyses. In addition, bibliometric programming frameworks exist for the programming languages Python (Tethne (github.com/diging/tethne (accessed on 11 June 2021)), Bibliotool [50], metaknowledge [51]), and R (bibliometrica [4]). They can be used to generate bibliometric networks; however, the computation for most of these frameworks is not implemented in parallel. In addition, programming skills are required. The respective analyses can be flexibly parameterized, but this requires extensive knowledge in dealing with bibliometric analyses. The presented bibliometric tools and the programming frameworks have in common that bibliometric data, in contrast to the seamless and automated integration in ambalytics, have to be exported manually from a bibliometric data provider and, subsequently, imported into the respective tool. Furthermore, web-based solutions exist that use bibliometric or comparable analyses. CoCites (cocites.com (accessed on 11 June 2021)) calculates co-citations of publications and is a browser plugin that displays a button below recognized publications for standard publication search engines, like Google Scholar (scholar.google.com (accessed on 11 June 2021)) and PubMed [52]. The number of found co-citations is displayed. A click on the button leads to a list of co-citations. CoCites only supports the calculation of co-citations and does not offer any other functions in addition to the publication list. ConnectedPapers (connectedpapers.com (accessed on 11 June 2021)) is a website that displays thematically similar publications as a graph based on a publication using co-citation and bibliographic coupling. In contrast to the ambalytics platform, only an initial single seed of a publication is supported instead of a full-text search. Furthermore, ConnectedPapers does not offer the possibility to customize the applied algorithm. The graph component is limited to the display of fewer than 50 nodes. In contrast to ambalytics, an HTML5 canvas is used, which leads to a (1) frame rate below 20 per second and (2) noticeable delays when panning and zooming the graph, even with a set of 50 nodes. According to its information, SemanticScholar is used as bibliometric data provider [53]. However, there is no information on the infrastructure structure or used technologies provided. Inciteful (inciteful.xyz (accessed on 11 June 2021)), similar to ConnectedPapers, generates a publication graph based on a single seed publication and subsequent deep search. Inciteful is programmed in Rust and does not use a scalable infrastructure. The Microsoft Academic Graph is used as the bibliometric data source, the web-based interface is programmed in React (reactjs.org (accessed on 11 June 2021)) and presents publication abstracts from SemanticScholar. Similarity between two publications is calculated using the Adamic/Adar algorithm: It is defined as the sum of the inverse log degree centrality of the common neighbors of two nodes [54]. An advantage of Adamic/Adar is its time complexity of \(O(E)\) with \(E\) be the number of edges, respectively the number of citations. Thus, it is faster than calculating hybrid research fronts, whose time complexity is \(O(V^{2})\) with \(V\) be the number of publications.