I used four five gallon pails with cement and chained them together. The more I read, the more I am coming to believe that a single mushroom anchor would have been easier, more effective, and easily retrievable by comparison. I was reading something on this the other day, but your pop quiz caught me out. I'll have to hit the reset button and come up with the literature for you. As I recall, I wouldn't have been out of pocket any more than my home-made efforts.
“Scientists are people who build the Brooklyn Bridge and then buy it.”
Wm. F. Buckley, Jr.