Ключевые слова: 2017, 2018, abstract, april, august, background, black, blackboard, board, business, calendar, calender, chalk, chalkboard, concept, date, december, design, element, english, event, february, graphic, green board, january, july, jun, june, learn, letter, march, may, month, monthly, november, number, october, organizer, planner, school, september, sign, symbol, template, text, time, vision, white, word, year,