[1] DIEUDONN J. A., CARRELL J. B.: Invariant Theory. Academic Press. New York. 1971. MR 0279102

[2] ГУРЕВИЧ Г. Б.: Основы теории алгебраических инвариантов. Moскв 1948. Zbl 1154.94303

[3] HORÁK M., KRUPKA D.: First order invariant Einstein-Cartan variational structures. Internal. J. Theoret. Phys. 17, 1978, 573-584. MR 0529702

[4] KRUPKA D.: A Theory of Generally Invariant Lagrangians for the Metric Fields I. International Journal of Theoretical Physics, Vol. 17, No 5, 1978, 359-368. MR 0527720 | Zbl 0407.58003

[5] KRUPKA D.: A Theory of Generally Invariant Lagrangians for the Metric Fields II. International Journal of Theoretical Physics, Vol. 15, No 12, 1976, 949-959. MR 0503475