49. (bax: galileo galilei)

(baxma: sir isaac newton)
(bax: albert einstein)

+

(bax: carl friedrich gauss)

(bax: bernhard riemann)

(bax: david hilbert)

+

(baxma: euclid's element of geometry)
(baxma: elements of geometry and trigonometry)
(bax: philosophiae naturalis principia mathematica)