https://pingyou.com/papers/erdos-106.pdf
https://pingyou.com/papers/erdos-265.pdf
https://pingyou.com/papers/erdos-289.pdf
https://pingyou.com/papers/erdos-349.pdf
https://pingyou.com/papers/erdos-354.pdf
https://pingyou.com/papers/eleven-squares.pdf
https://pingyou.com/papers/fibonacci-monotile.pdf
https://pingyou.com/papers/qualia-1pg.pdf