N. A'campo and A. Papadopoulos, Notes on non-Euclidean geometry, Srasbourg Master Class on Geometry (A. Papadopoulos, pp.1-182, 2012.

N. A'campo and A. Papadopoulos, Area in non-Euclidean geometry, Sixteen essays on non-Euclidean geometry, 2018.

J. Casey, A Treatise on Spherical Trigonometry, and Its Application to Geodesy and Astronomy, with Numerous Examples, Read Books Ltd, pp.1-180, 2013.

J. De-tilly, ´ Etudes de mécanique abstraite, Mémoires couronnés et autres mémoires publiés par l'Académie royale de Belgique, vol.21, pp.1-99, 1870.

D. Slutskiy, De Tilly's mechanical view on hyperbolic and spherical geometries, Sixteen essays on non-Euclidean geometry, 2018.

L. Euler, Principes de la trigonométrie sphérique tirés de la méthode des plus grands et des plus petits, Mémoires de l'Académie des sciences de Berlin 9, vol.1755, pp.277-308, 1753.

L. Euler, Variae speculationes super area triangulorum sphaericorum. Nova Acta academiae scientarum imperialis Petropolitinae 10, 1797, Opera Omnia Series, vol.1, pp.253-266

L. Euler-;-v.alberge, R. Caddeo, and A. Papadopoulos, English translation by R. Caddeo, On the measure of solid angles, to appear in: Spherical geometriy in the eighteenth century, Texts and Commentaries, vol.1, pp.204-223

E. Frenkel and W. Su, The area formula for hyperbolic triangles, Sixteen essays on non-Euclidean geometry, 2018.

H. Kneser, Der Simplexinhalt in der nichteuklidischen Geometrie, Deutsche Math, vol.1, pp.337-340, 1936.

H. L. Lebesgue, Démonstration du théorème de Lexell, Nouv. Ann. Math, pp.24-26

A. M. Legendre, ´ Eléments de géometrie, avec des notes, pp.1-428

A. J. Lexell, English translation by R. Caddeo, to appear in: Spherical geometriy in REFERENCES the eighteenth century. Texts and Commentaries, Acta Academiae Scientarum Imperialis Petropolotinae, vol.1, pp.112-126, 1781.

N. I. Lobachevsky and P. , Edited and translated with a commentary by A. Papadopoulos, Heritage of European Mathematics, vol.4, 2010.

H. Maehara and H. Martini, On Lexell's theorem. T he, American Mathematical Monthly, vol.124, pp.337-344, 2017.

J. Milnor, The Schlafli Differential Equality, C ollected Papers, vol.1, 1994.

J. Milnor and W. Thurston, The geometry and topology of threemanifolds, P rinceton lecture notes, 1980.

A. Papadopoulos and W. Su, On hyperbolic analogues of some classical theorems in spherical geometry, Hyperbolic geometry and geometric group theory, pp.225-253, 2017.
URL : https://hal.archives-ouvertes.fr/hal-01630212

G. Papelier, ´ Eléments de trigonométrie sphérique, Librarie Vuibert, pp.1-178, 1930.

L. A. , Santaì o, Introduction to integral geometry, Actualités Scientifiques et industrielles 1198, 1953.

L. A. Santaló, Integral geometry on surface of constant negative curvature, D uke Math. J, vol.10, pp.687-704, 1943.

F. T. Schubert, ;. V. Alberge, R. Caddeo, and A. Papadopoulos, English translation by R. Caddeo, Solution of a problem on the sphere. To appear in: Spherical geometry in the eighteenth century. Texts and commentaries, Nova Acta Academiae Scientiarum Imperialis Petropolitanae, vol.4, pp.89-94, 1786.

J. Steiner, Sur le maximum et le minimum des figures dans le plan, sur la sphère et dans l'espace en général, pp.105-170

T. Terquem and . De-trigonometrie-sphérique, Construction de l'excès sphérique, Nouvelles annales de mathématiques, pp.17-23

E. B. , Vinberg: Volumes of non-Euclidean polyhedra, Uspekhi Matematicheskikh Nauk, vol.48, issue.2, pp.17-46, 1993.