@misc{tang2004mechanism,
  title = "Mechanism for reciprocal awareness of intent to initiate and end interaction among remote users",
  author = "Tang, John C and Mordecai, Nicole Y and Begole, James MA and Bhalodia, Janak R and Van Kleek, Max G",
  year = "2004",
  month = "may~4",
  note = "US Patent 6,731,308",
}