H. Cong, A. Liu, Y. Hao, L. Feng, Z. Slanina, and F. Uhlik. Ho2O@C84: Crystallographic Evidence Showing Linear Metallic Oxide Cluster Encapsulated in {IPR} Fullerene Cage of D2d(51591)-C84. Inorganic Chemistry, American Chemical Society (ACS), volume 58, issue 16, July 2019. A. Liu, M. Nie, Y. Hao, Y. Yang, T. Wang, Z. Slanina, H. Cong, L. Feng, C. Wang, and F. Uhlik. Ho2O@C74: Ho2O Cluster Expands within a Small Non-{IPR} Fullerene Cage of C2(13333)-C74. Inorganic Chemistry, American Chemical Society (ACS), volume 58, issue 8, April 2019. A. Liu, M. Nie, Y. Hao, Y. Yang, T. Wang, Z. Slanina, H. Cong, L. Feng, C. Wang, and F. Uhlik. Ho2O@C74: Ho2O Cluster Expands within a Small Non-{IPR} Fullerene Cage of C2(13333)-C74. Inorganic Chemistry, American Chemical Society (ACS), volume 58, issue 8, April 2019.