Some Properties of the Curvature Operator of a Riemannian Manifold. Grigorios Tsagas — 1971 Mathematische Zeitschrift
The Spectrum of the Bochner-Laplace Operator on the 1-Forms on a Compact Riemannian Manifold. Grigorios Tsagas Mathematische Zeitschrift
On the Surfaces Whose Normal Bundles Have Special Properties Grigorios Tsagas — 1974 Δελτίο της Ελληνικής Μαθηματικής Εταιρίας
The spectrum of the Laplace operator on conformally flat manifolds Grigorios Tsagas — 1985 Annales Polonici Mathematici
Killing forms in a riemannian manifold with boundary Grigorios Tsagas — 1970 Annali della Scuola Normale Superiore di Pisa - Classe di Scienze
On the Killing tensor fields on a compact Riemannian manifold. Tsagas, Grigorios — 1996 Balkan Journal of Geometry and its Applications (BJGA)
The spectra and the symmetric structure on a compact symmetric space. Tsagas, Grigorios; Kobotis, Apostolos — 1996 Balkan Journal of Geometry and its Applications (BJGA)