Simplify the following text for a Grade 8 native English-speaking person.
Original: In 1902 , seven of his first stories appeared in national magazines and over the next decade he wrote many short stories and articles , contributing to nationally published magazines including Harper 's Monthly Magazine and the Saturday Evening Post , as well as carrying out extensive research on his family 's genealogy .
Simplified: Over the ten years , he wrote many short stories and articles . These were published in well-known magazines including Harper 's Monthly Magazine and the Saturday Evening Post .