0-9
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
... as "either of those element(s) of the field whose square equals b2 - 4ac". In some fields, some elements have no square roots and some have two; only zero has just one ...