Figures A and B above are two examples illustrating how "nodes" and "node notations" are formed by using 3 matchsticks. There are 7 more "node notations" using only 3 matchsticks. Can you find them all?
The rules are:
1. Matchstick heads can be ignored
2. All matchsticks must be flat on the surface
3. Each matchstick must touch at least one other matchstick