The best source for sports grounds and equipment dimensions can vary depending on the specific sport you're interested in. However, some general recommendations for finding accurate and reliable information include:

Official governing bodies: Many sports have official governing bodies or organizations that provide detailed regulations and standards for sports grounds and equipment. These organizations often have official websites sports dimensia where you can find comprehensive guidelines, dimensions, and regulations for various aspects of the sport. Examples include FIFA for soccer, FIBA for basketball, World Rugby for rugby, and the International Tennis Federation (ITF) for tennis.