An official website of the United States government
Here’s how you know
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.
ginning with the balanced incomplete block designs known as Youden Spuares, W.J. Youden created many designs tailored to the needs of the physical and engineering sciences.