Yep treasure maps are awesome. I found Treasure Map III, IV and X so far. So there is at least ten of them..

The only one that i found so far was the treasure of the tenth map, i knew the location, but the other two is hard and i have no idea where is it

I have three and four as well, I found both of their treasures. It was fun to search around and look and relook at the map, so I won't ruin it for you by telling you where to find the loot.
I'm really happy that Bethesda has chosen to go back to what they did in Morrowind with books. Lore books for all the lore lovers, treasure books and maps for all the treasure lovers, stories for story lovers and of course skill books that you don't even have to read to gain the benefit of. This game is so rich and full of life, I can't help but be ecstatic whenever I play and find something new.