@techreport{plt-tr2010-htdc-v4.2.4,
  author = {Kathryn E. Gray},
  title = {How to Design Classes Languages},
  number = {PLT-TR2010-htdc-v4.2.4},
  type = {Reference Manual},
  institution = {PLT Scheme Inc.},
  month = {January},
  year = {2010},
  url = {http://download.plt-scheme.org/doc/4.2.4/pdf/htdc.pdf},
  note = {\url{http://plt-scheme.org/techreports/}}
}