Sources:

2006 West Nickel Mines School shooting - Wikipedia

'The happening': 10 years after the Amish shooting | Pennsylvania | The Guardian

Forgiven: The Amish School Shooting, a Mother's Love, and a Story of Remarkable Grace: Terri Roberts, Windle, Jeanette, Lewis, Beverly: 9780764217326: Amazon.com: Books

StoryCorps: A Decade After Amish School Shooting, Gunman's Mother Talks Of Forgiveness : NPR

Gunman kills five students at Amish school | October 2, 2006 | HISTORY

Charles Carl Roberts | Murderpedia, the encyclopedia of murderers