Evaluating the Effectiveness of Google Scholar, ScienceDirect, Mendeley, and eLibrary for Interdisciplinary Research

As the volume of new scientific evidence, new ideas and practical developments increases, so does the risk that researchers will fall behind the current state of the science and its practical applications. A high-quality synthesis of information in the form of systematic reviews and meta-analyses aims to address this problem and can significantly facilitate the researchers' orientation in the current state of the scientific field. The following four search engines were selected for the methodology of this study: Google Scholar, ScienceDirect, Mendeley and eLibrary. Information was searched in various scientific disciplines, including machine learning, economics, and ecology. For the comparative analysis of the search engines, a keyword search was performed for the following terms: "climate warming", "ecological service", "reforestation", "wildfires", "ecological indicator", "cryptocurrency", "financial market", "machine learning", "market prediction", and "blockchain". For more complex queries, the following was searched: "machine learning" and "cryptocurrency", "machine learning" and "financial market", "machine learning" and "reforestation", "machine learning" and " wildfires". The search was conducted in February 2025 for the last 10 years (from 2015 to 2024). As a result, it was found that the search engines Google Scholar, ScienceDirect, Mendeley and eLibrary have significant differences that need to be taken into account when organizing searches. However, it is not recommended to use only one search engine in the study as this may lead to false conclusions. It is confirmed that Google Scholar returns significantly more records than other search engines. However, this search engine should not be used as the main source of information because of the low reproducibility of the results and the need for a great deal of effort to verify the relevance of the records. ScienceDirect and Mendeley provide similar results and may be suitable as a primary search engine. Google Scholar and eLibrary can be used as additional resources to increase the completeness of coverage of relevant publications. In conclusion, the analysis of searches carried out can help researchers choose the most appropriate search engine for specific research and may contribute to the writing of high quality systematic reviews.