Analysis of information sources in references of the Wikipedia article "Grama" in Portuguese language version.
Most of the world uses the metric system to weigh and measure. This book puts metric first, followed by imperial because the US uses it (with slight modifications which need not concern us).[ligação inativa]
The system of measurement used in the United States is complicated. Even when people have used the system all their lives, they still sometimes have trouble remembering things like how many fluid ounces are in a quart or how many feet are in a mile. ... The United States is the only major country that uses almost exclusively the complex system of measurement we have just described.