PubMed
https://pubmed.ncbi.nlm.nih.gov/ https://biblio.udb.edu.sv/biblioteca/wp-content/uploads/2021/06/48.jpg
Base de datos
Directorio de la Energía
http://directoriodelaenergia.es/inicio/proyecto.php https://biblio.udb.edu.sv/biblioteca/wp-content/uploads/2021/06/47.jpg
Cochrane Library
https://www.cochranelibrary.com/ https://biblio.udb.edu.sv/biblioteca/wp-content/uploads/2021/06/46.jpg
Biblioteca Virtual en Salud
https://elsalvador.bvsalud.org/ https://biblio.udb.edu.sv/biblioteca//wp-content/uploads/2021/06/45.jpg
Banco Mundial
https://datos.bancomundial.org/ https://biblio.udb.edu.sv/biblioteca/wp-content/uploads/2021/06/44.jpg
Research4Life
https://portal.research4life.org/ /https://biblio.udb.edu.sv/biblioteca/wp-content/uploads/2021/06/41.png
E-libro cátedra
https://elibro.net/es/lc/bibliotecaudb/inicio /biblioteca/wp-content/uploads/2021/06/14.jpg
