Or, go straight to the puzzles themselves.
If you haven't already, go to Google's puzzle series, and check out the LatinSquares applet.
If you liked that one, you'll want some more. We've got 'em here! Beats heck out of that boring rectangular thing with all the numbers, in my opinion.
The puzzle compiler -- who used to write 'Number Place' puzzles for Dell Magazines -- was looking around for some examples, so I sent him a few, from which he apparently chose at least some of the "symbol" series. Haven't gotten that far myself, so I can't say for sure.