Entry types:
% article.
%  must: author, title, journal, year
%  opt: volume, number, pages, month, note
% book.
%  must: author or editor, title, publisher, year
%  opt: volume or number, series, address, edition, month, note
% misc.
%  must: none
%  opt: author, title, howpublished, month, year, note
@manual{jpegspec,
    title = "Information Technology -- Digital Compression and Coding of
        Continuous-Tone Still Images -- Requirements and Guidelines",
    organization = "ITU",
    note = "ITU. ISO/IEC 10918-1:1993(E). CCITT Rec. T.81 (1992 E)",
    month = "September",
    year = "1992"
}