- Oaister [Link]
- International open repository wth academic resources.
- Recolecta [Link]
- Spanish open repository with academic resources
- E-Ciencia [Link]
- Open repository with academic resources from the Madrid province.
- Archivo Digital UPM [Link]
- Open repository with academic resources from the Universidad Politécnica de Madrid.
- FreeFullPDF [Link]
- International open repository with academic resource. It indexes more than 80 million free references (mostly to journal articles, theses, patents and posters.
