@Article{Byl90,
    Author       = "Byli{\'n}ski, C.",
    Year         = "1990",
    Title        = "{Functions from a Set to a Set}",
    Journal      = "Journal of Formalized Mathematics",
    Volume       = "1",
    Number       = "1",
    Pages        = "153-164",
    Comment      = "TPTPRef"
}

@Article{Byl90,
    Author       = "Bylinski, C.",
    Year         = "1990",
    Title        = "{Functions and Their Basic Properties}",
    Journal      = "Journal of Formalized Mathematics",
    Volume       = "1",
    Number       = "1",
    Pages        = "55-65",
    Comment      = "TPTPRef"
}

@Article{Byl90-Sets,
    Author       = "Bylinski, C.",
    Year         = "1990",
    Title        = "{Some Basic Properties of Sets}",
    Journal      = "Journal of Formalized Mathematics",
    Volume       = "1",
    Number       = "1",
    Pages        = "47-53",
    Comment      = "TPTPRef"
}