Weinberg, Jonathan (1997). «Rating the Net». Hastings Comm/Ent L.J.19: 453. Archivado desde el original el 11 de junio de 2021. Consultado el 15 de septiembre de 2015. «The Voluntary Content Rating self-rating system promoted by CYBERSitter is almost the model of a standard; it offers as its only guidance the instructions that self-raters should determine whether their sites are "not suitable for children under the age of 13," and whether they include material "intended for an audience 18 years of age or older."».
Weinberg, Jonathan (1997). «Rating the Net». Hastings Comm/Ent L.J.19: 453. Archivado desde el original el 11 de junio de 2021. Consultado el 15 de septiembre de 2015. «The Voluntary Content Rating self-rating system promoted by CYBERSitter is almost the model of a standard; it offers as its only guidance the instructions that self-raters should determine whether their sites are "not suitable for children under the age of 13," and whether they include material "intended for an audience 18 years of age or older."».