text: Luger, George; Stubblefield, William (2004).*Artificial Intelligence: Structures and Strategies for*
  *Complex Problem Solving*(https://archive.org/details/artificialintell0000luge) (5th ed.). 
  Benjamin/Cummings. ISBN 978-0-8053-4780-7. Archived (https://web.archive.org/web/2020 
  0726220613/https://archive.org/details/artificialintell0000luge) from the original on 26 July 
  2020. Retrieved 17 December 2019. 
  
  Nilsson, Nils (1998).*Artificial Intelligence: A New Synthesis*(https://archive.org/details/artificialin 
  tell0000nils). Morgan Kaufmann. ISBN 978-1-5586-0467-4. Archived (https://web.archive.or 
  g/web/20200726131654/https://archive.org/details/artificialintell0000nils) from the original on 
  26 July 2020. Retrieved 18 November 2019. 
  
  Russell, Stuart J.; Norvig, Peter (2003),*Artificial Intelligence: A Modern Approach*(http://aima.c 
  s.berkeley.edu/) (2nd ed.), Upper Saddle River, New Jersey: Prentice Hall, ISBN 0-13- 
  790395-2. 