# Progress in the Knowledge, Application and Influence of Extremely Low Frequency Signals
## 3 Results and Discussion  
After searching for the keywords, a total of 12,436 documents were obtained with a total of 42,813 relations between authors, established from 1956 to December 2019. After carrying out the debugging process to avoid the collection of unnecessary information, the number of works was reduced to 40.73%, leaving 5028 documents and 72.2% of the total relationships. Figure 1b shows the total work after the purification process and the relevant statistical treatment--it shows the distribution of all documents in a total of 12 communities. Each publication is represented by nodes and its size depends on its relationships. This representation allows the establishment of a common metric with other search engines such as Google Scholar as well as a metric of the collaborations between the authors. An author who has a well published and is highly referenced, but who works by himself will only be represented by a smaller node than another less referenced work, but which has greater collaborations with others. In this figure, we can distinguish three zones in which the largest communities are located. One of these areas is located in the upper left of the figure where three communities can be distinguished, another area is the central area where two communities are observed, one of them  
Figure 1: Representation of the communities investigating extremely low frequency (ELF). (a) Representation of the total untreated communities. (b) Representation of communities after debugging. being the largest compared to the rest, and the last one is the area located in the lower part of the figure, where there are three communities that are related to each other, one of them being somewhat superior to the rest. Figure 2 shows the documents making up each of the communities according to their colors. This representation is necessary, because due to the interrelationships present in Figure 1b, it is difficult to precisely determine the size of each of these communities. Each community is assigned a representative title gained from the research topic of the documents forming it. After carrying out a preliminary analysis of each of the communities separately, it was noted that some communities have the keywords established in the search, but their meaning is very different from that considered in this work. These communities belong to the field of molecular biology and genetics: these are the ELF transcription factors, ELF-1 in cancer and ELF-1 in the brain. These communities have the same theme, the ELF-1 gene, a gene that encodes a transcription factor related to the specific E26 transformation and they are related to each other as indicated in Figure 3b. The largest community is the ELF transcription factors community, represented with orange, which encompasses 5.91% of the total work found. This community deals with general aspects derived from the ELF subfamily, one of the largest families of exclusive transcription factors of animals. The transcription factors that constitute this ELF group are ELF1, ELF2 formerly known as new ets-related factor (NERF), and ELF4 or myeloid elf-1-like factor (MEF). Some documents from this community deal with the necessary actions for the improvement of a new protein related to ELF1 [42], the study of new ELF1 transcription factors [43], the functions or standards of ELF4 factors [44], or how these ELF1 factors can be related to virus regulation for human immunodeficiency [45]. It is the central point from which the ELF-1 in cancer and ELF-1 in the brain communities derive, with sizes of 0.6% and 0.5% respectively. Figure 3b shows the number of documents present in each of these communities, considering that the largest volume is the ELF transcription factors community with 84.4% of the total work dealing with this issue, the other two communities are smaller than one tenth of the general  
Figure 3: Representation of the ELF communities transcription factors, ELF-1 in cancer and ELF-1 in the brain. (**a**) Representation of the interaction of communities together.