Instruction books
Primers (Textbooks)
School books
Schoolbooks
Text books

ERIC thesaurus, July 28, 2014 (Textbooks. UF History Textbooks; Programed Texts; Supplementary Textbooks. BT Books; Instructional Materials. NT Multicultural Textbooks)
Art & architecture thesaurus online, July 28, 2014 (textbooks. UF text books; text-books; texts (instructional materials). Books used as standard works for the formal study of a particular subject.)
Genre terms : a thesaurus for use in rare book and special collections cataloging, via WWW, July 28, 2014 (Textbooks. UF Handbooks; Instruction books. BT Instructional works (Gathering term; do not assign). NT Alphabet books; Chrestomathies; Grammars; Hornbooks; Primers (Instructional books); Readers; Spellers)
Reitz, J.M. ODLIS : online dictionary for library and information science, July 28, 2014 (primer: Originally, a Book of Hours. Later, a book, often illustrated, written for young children to teach them how to read and spell. Synonymous in this sense with Dick and Jane book. See also: abecedary, battledore, horn book, and speller. In a more general sense, any book that gives the first principles of a subject or basic instruction for beginners.)
Görlach, M. An alphabetical list of English text types, in Text types and the history of English, c2004: p. 82 (textbook)