http://repositorio.umsa.bo/bitstream/handle/123456789/11563/EG-1332-Choque%20Cruz%2C%20Juan%20Jos%C3%A9.pdf?sequence=1&isAllowed=y http://www.ddgi.cat/municipis/Vilademuls/vodafone/proyecto%20t%C3%A9cnico%20vilafreser%20ap7.pdf