C. Schaper, “Geometric Origin of the Photosynthetic Macrocycle: Dual-Chrysene Cage Rearrangement, 18 pi-Electron Conservation, and the 1.1 Ga Geoporphyrin Record”, ACF, vol. 1, no. 1, pp. 233–247, Sep. 2026, doi: 10.68366/p1ykdx38.