An official website of the United States government
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Although Handbook No. 60 went out of print, because of continued interest in the handbook, this historic document is reproduced here in electronic format for the interested reader.