• https://dspace.itred.edu.ec/items/fe170129-5101-4780-a1e7-793a350c2f43
• https://dspace.itred.edu.ec/items/ff817a0a-e66d-4f9e-8193-4c604b301e24
• https://dspace.itred.edu.ec/items/ff9f0464-3ea6-488a-95d7-2301512b90db
• https://dspace.itred.edu.ec/items/ffc8f310-1eb2-4e7d-83c0-5132411421c5
• https://dspace.itred.edu.ec/items/ffe32a70-4158-496b-8568-7f9d24bc8349