## 3 Methodology
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Type**} & \multirow{2}{*}{**SEO/ASEO factor**} & **Google** & \multirow{2}{*}{**Google Scholar**} & **Microsoft** & \multirow{2}{*}{**WoS**} & **Scopus** \\  & & & **Search** & & & **Academic** \\ \hline \multirow{4}{*}{\begin{tabular}{c} On-page \\ factors \\ \end{tabular} } & Keywords in title & Yes [16; 17; 18; 19; 28; 29; 30] & Yes [31; 32] &? & Yes [40] & Yes [41] \\  & Keywords in URL, h1 or first & Yes [16; 17; 18; 19; 28; 29; 30] &? &? & No [40] & No [41] \\  & keyword frequency & No [16; 17; 18; 19] &? &? & Yes [40] & Yes [41] \\  & Technical factors. design, & Yes [16; 17; 18; 19; 28; 29; 30] &? &? & No [40] & No [41] \\  & speed, etc. & & & & & & \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} Off-page \\ factors \\ \end{tabular} } & Backlinks & Yes [16; 17; 18; 19; 28; 29; 30] &? &? & No [40] & No [41] \\  & Received citations &? & Yes [16; 31; 32; 33; 34] & Yes [35; 36; 37; 38; 35; 38; 36; 34; 35; 38; 37; 39; 40] & No [41] \\  & Author reputation & Yes [16; 17; 18; 19; 28; 29; 30] & Yes [16] & Yes [35; 36; 38; 36; 37; 38; 36; 38; 36; 39; 40] & No [41] \\  & Reputation of the publication & or domain & Yes [16; 17; 18; 19; 28; 29; 30] & Yes [16] & Yes [35; 36; 37; 38; 39; 40] & No [41] \\  & Signals from social networks & Yes (Indirect) &? &? & No [40] & No [41] \\  & Traffic, Click Through Rate & Yes [16; 17; 18; 19; 28; 29; 30] &? &? & No [40] & No [41] \\ \hline \multirow{2}{*}{
\begin{tabular}{c} Artificial \\ intelligence \\ \end{tabular} } & RankBrain & Yes [17; 18; 19; 28; 29; 30] &? &? & No [40] & No [41] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Search engine optimization (SEO) and academic search engine optimization (ASEO) factors. to be high. In reverse engineering studies with Google, the correlation values between the positions of the pages and the quantitative values of the supposed positioning factors do not normally exceed 0.3 [68]. Although the correlations are low, with studies of this type, relatively clear indications of the factors intervening in the ranking can be obtained. Google themselves provide even less data on how they rank by relevance in Google Scholar. Perhaps their most explicit statement is the following:  
\"Google Scholar aims to rank documents the way researchers do, weighing the full text of each document, where it was published, who it was written by as well as how often and how recently it has been cited in other scholarly literature.\" [71]. Previous research [64; 72] has shown that Google Scholar applies far fewer ranking factors than is the case with Google's general search engine. This is a great advantage when applying reverse engineering since the statistical results are much clearer, with some correlations being as high as 0.9 [34]. Likewise, Microsoft Academic does not offer any specific details about its relevance ranking algorithm [73]. We do know, however, that it applies the Microsoft Academic Graph or MAG [74], an enormous knowledge database made up of interconnected entities and objects. A vector model is applied to identify the documents with the greatest impact using the PopRank algorithm [13; 75]. However, Microsoft Academic does not indicate exactly what the \"impact\" is when this concept is applied to the sorting algorithm:  
\"In a nutshell, we use the dynamic eigencentrality measure of the heterogeneous MAG to determine the ranking of publications. The framework ensures that a publication will be ranked high if it impacts highly ranked publications, is authored by highly ranked scholars from prestigious institutions, or is published in a highly regarded venue in highly competitive fields. Mathematically speaking, the eigencentrality measure can be viewed as the likelihood that a publication will be mentioned as highly impactful when a survey is posed to the entire scholarly community\" [76]  
Unlike these two engines, the WoS and Scopus bibliographic databases provide detailed information about their relevance ranking factors [39; 40].