Retrieved 17 October 2010. ...multiple scratch scarifications by an instrument known as the Heaf gun (also known by the Trademark "Sterneedle"), or by...
Truy cập ngày 17 tháng 10 năm 2010. ...multiple scratch scarifications by an instrument known as the Heaf gun (also known by the Trademark "Sterneedle"), or by...  ^ “Heaf Test”.