Single leg partial squat

In 1999 (and on a few other occasions) I published and claimed copyright on this exercise description (bolding added now):

Single leg partial squat

Stand on the edge of a low block (1/3 to 1/2 the height of normal bench height). Have the weak leg on the box and the strong leg off the edge of the box. With your hands on your hips, bend at the knee of the weak side, lowering down (two to three seconds) until the sole of your feet almost brushes the floor.

Keep the sole parallel to the ground. Pause for one second and return to full extension in about one to two seconds. At the tenth rep, pause at the bottom position for ten seconds. You must not rest the non-supporting leg on the ground at any stage during the set. Then continue reps until you get to 20. Repeat the ten-second pause.

Can you go on? If yes, remember that you have to finish what you start—this exercise must be done in multiples of ten, with a ten-second pause in the bottom position at the completion of every ten reps. If you get to 50 reps, look to raise the height of the block.

If possible, don't hold onto anything during the set — the challenge of having to balance yourself will add to the fatigue. However, you may wish to do this near a wall or squat stand, just in case. You don't need to do a warm-up set; go straight into the work set. And be careful when you get off the block at the end of the set.

Repeat with the strong leg.

I was conducting research and I came upon the following exercise in a publication copyright claimed by another 'author' at a subsequent date (bolding added):

Single leg partial squat :

Stand on the edge of a low block (e.g. 1/3 to ½ the height of a normal bench height). Have the weak leg on the box and the strong leg off the edge of the box. Bend at the knee of the weak side, lowering down (2-3 seconds) until the sole of your feet almost brushes the floor.

Keep sole parallel to ground. Pause for 1 second and return to full extension in about 1-2 seconds. At the 10th rep, pause at the bottom position for 10 seconds. You must not rest the non-supporting leg on the ground at any stage during the set. Hands on hips. Then continue reps until you get to 20. Repeat the 10-second pause.

Can you go on? If yes, remember, what you start you must finish - this exercise must be done in multiples of 10, with a 10 second pause in bottom position at the completion of every 10 reps. If you get to 50 reps, look to raise the height of the block.

Preferably don’t hold on to anything during the set - the challenge of balance will add to the fatigue. However you may wish to do this near a wall or squat stand just in case. You don’t need to do a warm up set - get straight into the work set.

And I said to myself: “That looks familiar!” So I cross-referenced it and I said to myself: “Wow! No wonder that looked familiar!”

And I came upon this description another once or so more times by the same 'author' in different publications.

I noted that the use of this description was in the absence of credits or references to the origin or permission to use from the original author (myself), and that the 'author' claimed copyright....