Yongsong Wang, Fengming Chen, Xiao Guo, Jinxin Liu, Junjie Jiang, Xiaoming Zheng, Zihan Wang, Mansour M. Al-Makeen, Fangping Ouyang, Qinglin Xia, and Han Huang(黄寒)*. In-Plane Phonon Anisotropy and Anharmonicity in Exfoliated Natural Black Arsenic