1. T. Branson, “Spectra of self-gradients on spheres,” J. Lie Theory 9 (2), 491–506 (1999).
2. E. Stein and G. Weiss, “Generalization of the Cauchy–Riemann equations and representations of the rotation group,” Amer. J. Math 90, 163–196 (1968).
3. M. V. Smolnikova and S. E. Stepanov, “Fundamental first-order differential operators on exterior and symmetric forms,” Russian Math. (Iz. VUZ) 46 (11), 51–56 (2002).
4. S. E. Stepanov and M. V. Smolnikova, “Affine differential geometry of Killing tensors,” Russian Math. (Iz. VUZ) 48 (11), 74–78 (2004).
5. K. Heil, A. Moroianu and U. Semmelmann, “Killing and conformal Killing tensors,” J. Geom. Phys. 106, 383–400 (2016).