Ключевые слова: background, blank, book, bookshelf, bookstore, collection, color, concept, cover, document, education, exercise, experiment, forensics, group, handbook, hardcover, heap, industry, information, instrument, isolated, knowledge, learning, library, life, literary, literature, magazine, manual, nobody, object, open, optical, optics, page, paper, pencil, reading, research, school, stack, still, studio, studying, symbol, technology, text, textbook, white, wisdom,