http://web.missouri.edu/~cceric/sn/index.html Brass Instrument Serial Numbers Serial Numbers and the relevent information to calculate the age of your horn. Includes numbers for Bach, Besson, Conn, Holton, King, and Olds instruments. http://www.whc.net/rjones/connindex.html Conn Model Numbers Index Information about C. G. Conn Brass Instrument Model Numbers and Dates of Manufacture. http://www.whc.net/rjones/callet.html Jerome Callet's List of Serial Numbers List of serial numbers for Callet, Bach, Benge and Calicchio brass instruments. Date your instrument. http://www.musictrader.com/serialnos.html Proprietary serial number lists From Lars Kirmser's Music Trader site. Numbers for Bach, Benge, Besson, Blessing, Boston, Brua C. Keefer, Calicchio, King, Conn, Getzen, Holton, Martin, Mirafone, Olds, Reynolds, Schilke, and York, among others. http://web.calstatela.edu/faculty/jswain/brass/provsnl.htm York Provisional Serial Number List Numbers for the J.W. York Company.