Leopoldo Alas (Clarín), "Galdós" in Obras completas, tomo I, Madrid, 1912.
L. Antón del Olmet and A. García Carraffa, Galdós, Madrid, 1912. [Contains the most information.]
"El Bachiller Corchuelo" (González Fiol), "Benito Pérez Galdós," in Por esos mundos, vol. 20 (1910, I), 791-807; and vol. 21 (1910, II), 27-56. [Important.]
William Henry Bishop, in Warner's Library of the World's Best Literature, vol. XI, pp. 6153-63.
"El Caballero Audaz" (José María Carretero), Lo que sé por mí, 1ª serie, Madrid, 1915, pp. 1-11.
E. Díez-Canedo, "La Vida del Maestro," in El Sol, Jan. 4, 1920.
Archer M. Huntington, "Pérez Galdós in the Spanish Academy," in The Bookman, V (1897), pp. 220-22.
Rafael de Mesa, Don Benito Pérez Galdós, Madrid, 1920.
Emilia Pardo Bazán, "El Estudio de Galdós en Madrid," in Nuevo teatro crítico, agosto de 1891, pp. 65-74. (Obras completas, vol. 44.)
B. Pérez Galdós, "Memorias de un desmemoriado," in La esfera, vol. III, 1916 (especially the first two instalments).