%% You should probably cite rfc2637 instead of this I-D.
@techreport{ietf-pppext-pptp-10,
    number =    {draft-ietf-pppext-pptp-10},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-ietf-pppext-pptp/10/},
    author =    {Glen Zorn and Gurdeep-Singh Pall and Kory Hamzeh},
    title =     {{Point-to-Point Tunneling Protocol (PPTP)}},
    pagetotal = 57,
    year =      1999,
    month =     apr,
    day =       29,
    abstract =  {This document specifies a protocol which allows the Point to Point Protocol (PPP) to be tunneled through an IP network. This memo provides information for the Internet community.},
}