Lee, Hyunjin, Eunmi Pak, and Young Jin Suh. “Hopf Hypersurfaces in Complex Two-Plane Grassmannians With $\mathfrak{D}$-Parallel Shape Operator”. Mathematica Scandinavica 117, no. 2 (December 14, 2015): 217–230. Accessed July 24, 2026. https://journals.msp.org/mscand/article/view/376.