Dubouloz, A., I. Hedén, and T. Kishimoto. “Equivariant Extensions of $\mathbb{G}_a$-Torsors over Punctured Surfaces ”. ANNALI SCUOLA NORMALE SUPERIORE - CLASSE DI SCIENZE, vol. 21, no. special, 1-2, Dec. 2020, pp. 133-67, doi:10.2422/2036-2145.201710_002.