• https://repositorio.upn.edu.pe/items/f5efb183-1f09-47b3-9f92-ccd3d1ab4fae
• https://repositorio.upn.edu.pe/items/7fd8c356-a8cf-4be2-95e2-fa1a90115bce
• https://repositorio.upn.edu.pe/items/53f56cf2-979e-4e35-83a3-3f3934f4fc20
• https://repositorio.upn.edu.pe/items/161830cd-37d6-422c-9269-5504ef5d9aaa