Tham khảo LOL

  1. ↑ Matt Haig (2001). E-Mail Essentials: How to Make the Most of E-Communications. Kogan Page. tr. 89. ISBN 0-7494-3576-3. 
  2. ↑ Louis R. Franzini (2002). Kids Who Laugh: How to Develop Your Child's Sense of Humor. Square One Publishers, Inc. tr. 145–146. ISBN 0-7570-0008-8. 
  3. ↑ Michael Egan (2004). Email Etiquette. Cool Publications Ltd. tr. 32, 57–58. ISBN 1-84481-118-2. 
  4. ↑ Ann Hewings, Martin Hewings, Grammar and Context, An advanced Resource Book, Routledge Applied Linguistics, 2005, ISBN 0-415-31080-6
  5. ↑ Jimmi Harrigan, Robert Rosenthal, Methods in Nonverbal Behavior Research, Oxford University Press, 2005, ISBN 978-0-19-852962-0
  6. ↑ John P. Sloan, Instant English 2, Gribaudo, 2011 ISBN 978-88-580-0448-7