The catalog is an essential tool of collecting as it provides information about the articles that many times cannot be extracted from them directly, such as the number of printed banknotes.
In the 1950s, Robert Friedberg published the Paper Money of the United States.
[2] His collection of over 180,000 banknotes was eventually housed at the Bavarian Mortgages and Exchange Bank (Bayerischen Hypotheken- und Wechselbank, now HypoVereinsbank).
This catalog underwent several incarnations, and is currently published as a three volume group.
[4] Volume III covers Modern Issues dated 1960 to present.