Trilingual Education: Sign Language, Spanish, English by Professors Ben and Kathie Christensen, is a unique manual developed to facilitate the communication of clear concepts between Spanish-speaking parents and their deaf children. Using a series of clear exercises and diagrams, it provides a basic tool for interchange among users of three different languages: spoken English, spoken Spanish, and American Sign Language.
Most sign language books normally just have English content. Trilingual English has more than just English content (Spanish and Sign Language). It allows students who sign in Spanish to learn new words or phrases that they may haven't been taught before.
Amazon Link: https://www.amazon.com/Trilingual-Education-Language-Spanish-English/dp/0916304701/ref=sr_1_1?keywords=trilingual&m=A119ICNS1106UD&qid=1568414526&s=merchant-items&sr=1-1