32 books • 8 series
El mundo de la tecnolog a: Los inventos del siglo XX (Tech World: 20th Century Inventions) (Exploring Reading)
Ondas sonoras y la comunicaci n (Sound Waves and Communication) (Science Readers: Content and Literacy)
Fuerzas equilibradas y no equilibradas (Balanced and Unbalanced Forces) (Science Readers: Content and Literacy)