1. Blažić, N., Bokan, N., Rakić, Z.: The first order PDE system for type III Osserman manifolds. Publ. Inst. Math. (Beograd) (N.S.) 62(76), 113–119 (1997)
2. Blažić, N., Bokan, N., Rakić, Z.: A note on the Ossermann conjecture and isotropic covariant derivative of curvature. Proc. Am. Math. Soc. 128, 245–253 (2000)
3. Brans, C.H.: Complex 2-form representation of the Einstein equations: The Petrov type III solutions. J. Math. Phys. 12, 1616–1619 (1971)
4. Calviño-Louzao, E., García-Río, E., Gilkey, P., Vázquez-Lorenzo, R.: The geometry of modified Riemannian extensions. Preprint
5. Contemp. Math.;A. Derdzinski,2003