BellBoard

231456789					
431652978	s1, 2, s5, 8, 9, s13, s15, 16	
314256		(a)				|
123654		6, s8, s16	  |   A		|
231456		(a)		  |		|
1423		2A				|   C
134265		s3, 7, 12, 13, s18, s20		|
213497568	3, s5, s10, 12, 14, 17 #	|
231465789	1, 2, 3, s5, s10, 14, 17	|
231896745	1, 3-6, s8-12			|
987654321	7, 9, 12, 13
325164978	2, s4, 6, 7, 10, 12, 13, s15-18
2351		s4, s11, s13
263154		4-7, s8, s10, 12
142365		s1, 6, s8, s11, 12, 13, s15, 16
145263879	2, s9, 16
421365		(b)				
435162		3, 4, s11, 14-16  |   B
314265		(b)		  |		
325461		s15, 16
243165		(b)
1324		B				
412365789	7, 8, 12, 13, s18
432651978	1, 7, 8, s10-14
321896745	C, but call extra 13 in course marked #
325164789	s7, s9, s10, 16
134265		s4, s8, s11, s13, s16
241365879	5, s8, 12, 13, s16
1342		3B				

(a) = s3, 5, 13, 16.
(b) = 4, 5, 8, 9, 14, 15, 18, 19.