Takagi, Hiromichi. “Constructing Prime $\mathbb{Q}$-Fano Threefolds of Codimension Four via Key Varieties Related With $\mathbb{P}^2\times \mathbb{P}^2$-Fibrations”. MATHEMATICA SCANDINAVICA 131, no. 3 (October 23, 2025). Accessed December 5, 2025. https://www.mscand.dk/article/view/158550.