2.1. Structured Literature Review Method Variation

The SLR method variation is supported by the research queries exploring the Scopus database. The SLR has its own procedure, which is not presented in detail in this paper [53,54]. In this study, the SLR method is used as a tool for the identification of knowledge gaps and the future direction of the research collected in bibliographic databases [55]. The SLR method variation is based on the research queries, which are used to explore the Scopus database. In this paper, the whole Scopus database was researched without any limitation to specific years or periods. The subject of this study is metadata of scientific literature collected in the Scopus database. This database was selected due to its broad scientific recognition and wider collection of content than other databases [55,56]. The information related to the bibliometric records of the Scopus database were explored by the bibliometric visualization tool software. The results of this method are presented in form of bibliometric maps with the use of the VOSviewer program (version 1.6.18). This software is commonly used by researchers in bibliometric studies in different research areas [57,58]. The method used in this research is to perform bibliometric analysis to produce a network visualization of keywords for the queries. In the variation of the SLR method, the three original queries were formulated and developed as presented in Table 1. There are differences in the formulated queries, although the queries have a syntax that corresponds with the database on which they are used. There are different numbers of results depending on the number of used green job equivalents and variants such as green employment, green collar, environmental job, or sustainable job.

Queries focused on typologies used in the Scopus scientific database exploration on 20 August 2022.

Source: Authors’ elaboration.

The data presented in Table 1 and Table 2 queries’ construction and calibration are presented in Supplementary Materials File S1 in detail. These queries are focused on the GJs typologies visible in Scopus database-indexed publications. The subject areas in this research were not chosen automatically by the selection in the Scopus database but each paper was carefully reviewed to exclude misleading results to be further analyzed. This time-consuming operation explains the different dates presented in Table 1 and Table 2 results. There are differences in the formulated queries in Table 2, although the queries have a syntax that corresponds with the database on which they are used [59].

Syntaxes used in Queries after calibration for the Scopus scientific database exploration GJs concept.

Source: Authors’ elaboration.

Presented queries do not differ in the publication type, years, or category, because such filters were not used to explore the Scopus database. The results obtained from Queries 4 and 5 (Q4 and Q5, respectively) were downloaded each time as a set of files in .csv format and during the export procedure, all fields on the publication were marked. Further analyses were carried out on the collected data in the VOSviewer program and the results are shown in bibliometric maps [60].

This research has its own limitations because the choice of the number of co-occurrences determines the result obtained in its graphical presentation and bibliometric map clarity. Therefore, a minimum number of 10 keyword co-occurrences was set for each bibliometric map initially, then it was changed and indicated specifically before each figure with the bibliometric map. The VOSviewer program allows researchers to define the research gaps covered by the published paper and indicate the directions of scientific development [55]. The exploration of the scientific database, presented in Table 2 Q4 and Q5, leads to the comparison of the GJ variants in two sets of query results.