Ключевые слова: 4, added, assistant, background, ball, board, championship, change, competition, electronic, end, event, extra, field, football, four, game, hand, league, linesman, man, match, minute, national, people, pitch, play, professional, referee, replacement, representation, showing, sign, signal, six, soccer, sport, stage, substitution, team, technic, technical, tournament, up,