Cover to San Miguel de los Reyes prison in Valencia with censor

Cover franked with 30c Edifil 687 and 15c Edifil 747 to Luis Huelín Gorria, in San Miguel de los Reyes prison in Valencia. Censor mark "D.P. Nº 1 - VALENCIA / CENSURA". Sender's info on the back: Carmen Valdés, Atocha 113. Unreadable postmark, but Edifil 747 was issued in 1938, so the cover must have been circulated in 1938 or 1939.