On Aug. 31, 1990, Ken Griffey Jr. and Sr. became the first father-son teammates in MLB history

When Ken Griffey Sr. humorously 'grounded' Ken Griffey Jr. for catching a fly ball in his territory while playing with the Seattle Mariners

Ken Griffey Sr. once revealed his greatest achievement in famed MLB career

Junior's achievements: 24 of Ken Griffey Jr.'s most remarkable feats - ESPN

What father and sons have been in professional sports at the same time? - Quora

Donora's Ken Griffey Jr. an easy choice for Hall of Fame, Mon Valley

Ken Griffey Sr. and Jr. become first father/son combo to appear in the same lineup

From Attempted Suicide to MLB Superstar-The Life and Very Complicated Times of Ken Griffey Jr.

Vladimir Guerrero joins Vladimir Sr. as first father-son Home Run Derby winner

Ken Griffey Sr. and Jr. become the first father-son duo to ever play together

Ken Griffey Jr. - Wikipedia

Ken Griffey Jr. - Wikipedia