From one of my previous question Aperiodic set of corner Wang Tile (although it is put on hold), I realize there is a systematic way to construct aperiodic corner type of Wang tile from edge type aperiodic Wang Tiles. But what I am more interested in is this:

For edge type of Wang tile, there is common knowledge of a very small set of Wang tile with 13 elements: http://www.sciencedirect.com/science/article/pii/S0012365X96001185 or with 14 elements: http://www.sciencedirect.com.libproxy.mit.edu/science/article/pii/0012365X9500120L#

It seems there is a competition on this arena of achieving smaller set of aperiodic edge type of Wang tiles. On the other hand, I interested on a documented small set of corner Wang tiles. Do someone know some reference on this? Thank you:)