Differentiability along one-parameter subgroups compared to differentiability on Lie groups as manifolds
N. Nikitin, in: 50th Seminar “Sophus Lie”, Bdlewo, Poland, September 26 – October 1, 2016. Dedicated to Professor Karl Heinrich Hofmann on the Occasion of His 85th Birthday, Warsaw: Polish Academy of Sciences, Institute of Mathematics, 2017, pp. 363–373.

Differentiable mappings on products with different degrees of differentiability in the two factors
H. Alzaareer, A. Schmeding, Expositiones Mathematicae 33 (2015) 184–222.

Weighted diffeomorphism groups of Banach spaces and weighted mapping groups
B. Walter, Dissertationes Mathematicae 484 (2012) 126.