W. Gao, C. Addiego, H. Wang, X. Yan, Y. Hou, D. Ji, C. Heikes, Y. Zhang, L. Li, H. Huyan, T. Blum, T. Aoki, Y. Nie, D.G. Schlom, R. Wu, and X.Q. Pan, “Real-Space Charge-Density Imaging with Sub-Ångström Resolution by Four-Dimensional Electron Microscopy,” Nature 575 (2019) 480–484.