Books like Diccionario de Uso del Español
María Moliner
Diccionario de Uso del Español is 1,503 pages, about 27 hours 33 minutes at 250 words a minute.
6 books to read next
How long each takes
Spanish for Dummies 7.3 h 
Complete Spanish 5.6 h 
The Interpreter's Companion 6.5 h 
Pronouncing Dictionary of the Spanish and English Languages 14.5 h 
Glosario Internacional Para el Traductor = 11.8 h 
Diccionario de Mejicanismos 22.1 h Bar height shows length. Estimated at 250 words a minute.