Bibliography:
-------------

Ideas for the backtracking swapping algorithm:

[1] Michael Marte - Models And Algorithms For School Timetabling - 
A Constraint Programming Approach - ( free, on the internet, one possible link 
is: http://www.pms.ifi.lmu.de/publikationen/dissertationen/PMS-DISS-2003-1/PMS-DISS-2003-1.pdf ) 
- Section 2.2.5 - Manual Timetabling - pages 23-24.

[2] Jantien Hartog - Timetabling on Dutch High-Schools - 
Satifiability versus gp-Untis ( free, on the internet, one possible link 
is: http://www.st.ewi.tudelft.nl/sat/theses/jantien.pdf ) 
- Section 5.2 - page 27.
