Observaciones herpetológicas en Valladolid, el 19 de abril de 1952, sobre Natrix maura (Culebra viperina, llamada Tropidonotus viperinus por el autor) y Natrix natrix (Culebra de collar).
Herpetological observations of Valladolid, of the 19th of April of 1952, about Natrix maura (Viperine Snake, refered as Tropidonotus viperinus by the author) and Natrix natrix (Grass Snake).
