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.
One ivy leaf (Leaf 4) with printed grids on its surface. Each grid line is composed of discontinuous dots. The entire surface is divided into 700 small cells. Regions a (square), b (deformed square) and c (triangle) represent different shapes of the cells.
