@ARTICLE\{IMM1992-02073,
    author       = "P. Fischer and H. -. Simon",
    title        = "On Learning Ring-Sum-Expansions",
    year         = "1992",
    pages        = "181-192",
    journal      = "{SIAM} Journal on Computing",
    volume       = "21, 1",
    editor       = "",
    number       = "",
    publisher    = "",
    url          = "http://www2.compute.dtu.dk/pubdb/pubs/2073-full.html"
}