Electron Source	electron crystallography	helical	single particle	subtomogram averaging	electron tomography	sum
FIELD EMISSION	441	4303	76721	3310	2358	87133
LAB6	17	48	1346	49	516	1976
n/a	10	1	4	0	0	15
OTHER	3	8	547	9	18	585
TUNGSTEN HAIRPIN	2	25	212	2	28	269