Willems, H. (1995). Development, Patterns and Causes of Violence against Foreigners in Germany: Social and Biographical Characteristics of Perpetrators and the Process of Escalation. Terror from the extreme right.

Willems, Helmut. "Development, Patterns and Causes of Violence Against Foreigners in Germany: Social and Biographical Characteristics of Perpetrators and the Process of Escalation." Terror from the Extreme Right 1995.

Willems, Helmut. "Development, Patterns and Causes of Violence Against Foreigners in Germany: Social and Biographical Characteristics of Perpetrators and the Process of Escalation." Terror from the Extreme Right, 1995.