@techreport{
    NT87:hlm,
    author = {Niemel{\"a}, Ilkka and Tuominen, H.},
    title = "{Helsinki Logic Machine}: a System for Logical Expertise",
    address = "Espoo, Finland",
    number = "B1",
    month = "December",
    flags = "copy",
    year = "1987",
    type = "Technical report",
    institution = "Helsinki University of Technology, Digital Systems Laboratory"
}