It is a html link and a subdomain name that is the same as a protocol. Here pdf link: https://dl.acm.org/doi/pdf/10.1145/263698.263754 https://dl.acm.org/doi/

It is a html link and a subdomain name that is the same as a protocol. Here pdf link: https://dl.acm.org/doi/pdf/10.1145/263698.263754 https://dl.acm.org/doi/pdf/10.1145/263698.263754