[1] A. Browder:
Point Derivations on Function Аlgebras. J. Func. Аnal. 1 (1) 1967), 22-27.
MR 0211262
[2] A. P. Hallstrom:
On Bounded Рoint Derivations and Аnalytic Capacity. J. Func. Аnal. 4 (1) 1969, 153-165.
MR 0243358
[3] J. Wermer:
Bounded Point Derivations on Certain Banach Аlgebras. Ј. Func. Аnal. I (1) 1967,28-36.
MR 0215105