@techreport{
    haa04:minsum*1,
    author = {Haanp{\"a}{\"a}, Harri},
    title = "Minimum Sum and Difference Covers of {A}belian Groups",
    url = "http://lib.hut.fi/Diss/2004/isbn9512269422/",
    pages = "9",
    address = "Espoo, Finland",
    number = "A88",
    month = "February",
    flags = "copy",
    year = "2004",
    annote = "sci",
    type = "Research Report",
    institution = "Helsinki University of Technology, Laboratory for Theoretical Computer Science"
}