Fear of biographies.
Many are quite thick and heavy and can do real damage if they fall on you.
https://m.youtube.com/watch?v=q1-UiUoVL60&pp=ygUuQ2xldHVzLCBub3RoaW5nIGNyYWNrcyBhIHR1cnlsZSBsaWtlIGxlb24gdXJpcw%3D%3D