16 Educational books, namely, student text books, manuals, supplements, and guides on learning and teaching languages; teacher text books, manuals, supplements, and guides on learning and teaching languages; and administrator text books, manuals, supplements, and guides on learning and teaching languages; and other printed materials, namely, brochures, other than advertising brochures, about learning and teaching languages, catalogues on learning and teaching languages, printed posters, technical guides on learning and teaching languages, and business forms, namely specification documents and invoices