Tài liệu tham khảo WikiPedia: Ẩn_số_tình_yêu http://boxofficemojo.com/movies/?id=valentinesday.... http://www.boxofficemojo.com/movies/?id=valentines... http://latimesblogs.latimes.com/entertainmentnewsb... http://www.metacritic.com/movie/valentinesday http://www.valentinesdaymovie.com https://www.allmovie.com/movie/v491544 https://www.imdb.com/title/tt0817230/ https://www.rottentomatoes.com/m/valentines_day_20...
