1. Unwrapping the Secret Santa of Folklore: Unconventional Yuletide Traditions from Around the WorldSources:- [知乎 - 有问题,就会有答案] (https://www.zhihu.com/)- [Formal proof for $ (-1) imes (-1) = 1$ - Mathematics Stack …] (https://math.stackexchange.com/questions/304422/formal-proof-for-1-times-1-1)- [What is the value of $1^i$? - Mathematics Stack Exchange] (https://math.stackexchange.com/questions/3668/what-is-the-value-of-1i)- [abstract algebra - Prove that 1+1=2 - Mathematics Stack Exchange] (https://math.stackexchange.com/questions/278974/prove-that-11-2)- [Why is $1/i$ equal to $-i$? - Mathematics Stack Exchange] (https://math.stackexchange.com/questions/1277038/why-is-1-i-equal-to-i)- [矩阵的逆怎么算?逆矩阵公式来了 (附逆矩阵计算器)] (https://www.zhihu.com/tardis/bd/art/721779164)- [知乎 - 知乎] (https://www.zhihu.com/selection/)- [游戏评测的 1% 最低帧(1% Low FPS)是什么意思? - 知乎] (https://www.zhihu.com/question/334229181?write)- [factorial - Why does 0! = 1? - Mathematics Stack Exchange] (https://math.stackexchange.com/questions/25333/why-does-0-1)- [请问电容的储能公式W=1/2CU²是怎么推导出来的? - 知乎] (https://www.zhihu.com/question/629546895)