Ключевые слова: answer, book, booklet, business, businessman, catalog, client, concept, customer, data, design, document, education, element, faq, flat, graphic, gray background, guidance, guide, guidebook, hand, handbook, help, illustration, info, information, instruction, instructions, isolated, learn, magnifying glass, manual, object, paper, read, reference, search, service, sign, support, symbol, technology, textbook, training, tutor, tutorial, use, user,