1. Centralizers of immersions of the circle;Arteaga, Carlos;Proc. Amer. Math. Soc.,1990
2. Commuting diffeomorphisms;Kopell, Nancy,1970
3. Endomorphisms of compact differentiable manifolds;Shub, Michael;Amer. J. Math.,1969
4. Local 𝐶ⁿ transformations of the real line;Sternberg, Shlomo;Duke Math. J.,1957