@article{
    haa04:minsum,
    author = {Haanp{\"a}{\"a}, Harri},
    title = "Minimum Sum and Difference Covers of {A}belian Groups",
    url = "http://www.math.uwaterloo.ca/JIS/",
    journal = "Journal of Integer Sequences",
    number = "2",
    volume = "7",
    year = "2004",
    pdf = "haa04minsum.pdf",
    annote = "int journal ref",
    pages = "article 04.1.8"
}