return {
    ["GH0001"] = {
        category  = "book",
        title     = "Rhythmic Illusions",
        subtitle  = "for drums",
        author    = "Gavin Harrison",
        publisher = "Warner",
        isbn      = "1576236870",
        year      = "1996",
        comment   = "plus cd",
    },
    ["GH0002"] = { -- no reference in brittisch library
        category  = "book",
        title     = "Rhythmic Perspectives",
        subtitle  = "a multidimensional study of rhythmic composition",
        author    = "Gavin Harrison",
        publisher = "Alfred Publishing Co., Inc",
        year      = "1999",
        comment   = "plus cd",
    },
    ["GH0003"] = {
        category  = "book",
        title     = "Rhythmic Designs",
        subtitle  = "a study of practical creativity",
        author    = "Gavin Harrison and Terry Branham",
        publisher = "Hudson",
        year      = "2010",
        comment   = "plus dvd",
    },
}