F531.14
Gra
C
Graef - Fernandez , Carlos , 1911-
Carlos Graef Fernandez ....   (Ficha 2 ) 
pp. 167 - 189 , Garrett Birkhoff y R. E. Langer / eds / . Publicado por la American Mathematical Society , Providence, Rhode Island , 1959 ). Orbits in Birkhoff´s central field by Carlos Graef - Fernandez .
" Bibliography " : p. 188-189