@article{
    mrai83,
    author = {Mannila, Heikki and R{\"a}ih{\"a}, Kari-Jouko},
    volume = "20",
    journal = "Acta Informatica",
    year = "1983",
    pages = "143-158",
    title = "On the relationship of minimum and optimum covers for a set of functional dependencies"
}