Shi, S., F. Chen, S. Goel, S. A. Graves, H. Luo, C. P. Theuer, J. W. Engle, and W. Cai. “In Vivo Tumor-Targeted Dual-Modality PET/Optical Imaging With a Yolk/Shell-Structured Silica Nanosystem”. Nano-Micro Letters, vol. 10, no. 4, July 2018, p. 65, doi:10.1007/s40820-018-0216-2.