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• Madroño
  

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• MathSciNet
  

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• MEDLINE
  

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• MedlinePlus
  

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• MERLOT : Multimedia Educational Resource for Learning and Online Teaching
  

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• MeSH : Medical Subject Headings
  

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• Microsoft Academic
  

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• MLA International Bibliography
  

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• Moodle
  

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• MOREA : Múltiples Objetos Reutilizables para la Enseñanza y el Aprendizaje