Which preposition to use with phonogram

at Occurrences 1%

His study of the Chinese phonograms at length resulted in the transformation of his careworn face by a slowly dawning smile, the gleeful smile of a mischief-loving child.

of Occurrences 1%

He intends to bring home phonograms of the savage dialects which he will hire the natives to speak into the machine.

Which preposition to use with  phonogram