● Google Academico https://scholar.google.es
● Crossref (Metadata Search) https://search.crossref.org/
● Harvard Library https://library.harvard.edu/
● RefSeek – Academic Search Engine https://www.refseek.com
● WebMD https://www.webmd.com/
● WORDCAT https://www.worldcat.org/
● REDIB https://www.redib.org
● AmeliCA http://amelica.org
● Bases de datos Web Science https://www.recursoscientificos.fecyt.es
● Web of Science https://www.webofknowledge.com
