Previous lectures
#1, 1/25/07
#2, 1/30/07
#3, 2/1/07
#4, 2/6/07
#5, 2/8/07
#6, 2/15/07
#7, 2/20/07
#8, 2/22/07
#9, 2/27/07
#10, 3/1/07
#11, 3/6/07
#12, 3/8/07
#13, 3/13/07
#14, 3/27/07
#15, 3/29/07
#16, 4/3/07
#17, 4/5/07
#18, 4/10/07
#19, 4/12/07
#20, 4/17/07
#21, 4/19/07
#22, 4/24/07
#23, 4/26/07
#24, 5/1/07
#25, 5/3/07
#26, 5/8/07