Benedetto, E. (2011). Lie Group of Spacetime. ISRN Astronomy and Astrophysics, (), 107-113. https://www.airitilibrary.com/Article/Detail?DocID=20904738-201112-201202230026-201202230026-109-115
Saaidi, K., Mohammadi, A., & Golanbari, T. (2015). Light of Planck-2015 on Noncanonical Inflation. Advances in High Energy Physics, 2015(), 831-841-166. https://doi.org/10.1155/2015/926807