insertion sort with sentinels

Found two papers (wow.) on insertion sort with sentinels.
Using Sentinels In Insert Sort (1989) by Harold Thimbleby


Also An improved insert sort algorithm

Also Jon Bentley's method of insertion sort actually reduce one subtraction in the outside loop of straight insertion sort without sentinels.   Ah ,where is my "Programming Pearl"?   Who doesn't want to exhaust the topic as simple as insertion sort?

33_P