# Overview of Blockchain Oracle Research
## 7 Conclusions  
This paper undertook a bibliometric analysis of published studies about blockchain oracles. The aim was to display publication trends along with preferred outlets and publishers. The most-cited papers and authors and the most contributing institutions are also shown. After the selected literature was reviewed, emerging themes, research directions, and converging studies were discussed to promote innovation and cooperation between institutions. The obtained results show that, within seven years of academic production, only 162 papers (including non-peer-reviewed) were retrieved in scholarly databases. This result supports the view that blockchain oracle is still a widely neglected subject, despite its crucial importance. The review also reveals heterogeneity in the oracle literature; therefore, major efforts are required to find a widely accepted oracle taxonomy. Furthermore, limited oracle selection suggests the need for more active collaboration between practitioners and academia. Finally, more theoretical work is required on the underlying trust concept that identifies oracles as \"trusted\" ones. The findings of this research are useful for academics, students, and practitioners. Offering an overview of institutions investigating a specific field, this study can promote cooperation between existing or entering research teams in the blockchain oracle domain. This, in turn, can constitute a reference for entrepreneurs undertaking blockchain-based projects. Students and other academics can then utilize a resource on the state-of-the \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Field** & & **Theme/s** & \multicolumn{2}{c}{**Expected/Desired Outcomes**} \\ \hline \multirow{8}{*}{Oracle theory} & - & Contribute to a univocal oracle taxonomy & - & Make oracle literature more accessible to a broader audience \\  & & & - & Attract more research in the oracle field \\ \cline{2-4}  & - & Define the boundaries of oracles’ definition & - & Reduce heterogeneity within oracle literature \\  & - & Define the theoretical background to which the “trust” discussed in oracle literature & - & Develop more robust trust models \\  & & should adhere & - & Reduce the heterogeneity of proposals \\ \cline{2-4}  & - & Investigate resistant and trusted centralized oracle types & - & Adapt oracles to specific data types with limited sources. \\ \hline \multirow{8}{*}{Oracle applied} & - & Integrate oracles in digital rights & - & Broaden blockchain-based intellectual property use cases. \\  & - & Investigate robust links between physical products and the blockchain & - & Improve any blockchain-based application involving physical products (e.g., traceability). \\ \cline{1-1} \cline{2-4}  & - & Investigate emerging oracle solutions & - & Promote active collaborations between academia and oracle providers \\ \hline \hline \end{tabular}
\end{table} 
Table 14: Suggested research themes. art knowledge of related fields and investigate emerging gaps (e.g., missing resource management contributions) or create other research by building on existing studies. This paper also has limitations given the scarcity of retrieved material that determined low numbers in absolute terms in all the tables and figures. As specified in Section 3, a degree of subjectivity in the presented results cannot be excluded. Whereas previous studies inspired the method and bibliometric research, the author had to select them arbitrarily. Subjectivity can also be found in the sample classification, given that the division of topics into categories and sub-categories had to be performed manually. Again, the author wishes to reiterate that the data provided in this paper should not, in any case, be interpreted as a quality evaluation of the cited works. Because of the selection criteria, some works or authors may have been excluded inadvertently. Further studies can build on this bibliometric analysis to investigate the trust models adopted and presented in the published literature and the preferred oracle applications for academic investigations.