I was searching the posts for information on snare wire knots. I found 2 references to using a larks head. Can someone explain how that would work for me?

Aardwolfe mentioned that John’s SAS Guide recommends a slipknot on a slipknot. I have the Collins Gem edition if someone can give me a page number. I didn’t see it.
”As the animal struggles to get free, it not only pulls the main loop tight, it also tightens up the lark's head knot so the loop will not come loose.”

Shaggystu “…i don't think the larks head makes any difference to how effective the snare is at holding an animal, it just makes a difference as to how effective the snare is at killing animals.”

Thanks