Which preposition to use with trusteeship

of Occurrences 4%

* * * The Indian Office is the agency of the government for administering both the guardianship of the Indian and the trusteeship of his properties.

for Occurrences 3%

The nation is all of us, and its government is trusteeship for us all in order to give us peace and security, and in order that in peace and security we may make each other's lives worth living by doing each the best work he can.

toward Occurrences 2%

A better code of business morality has developed, and the railroad management's relationship of private trusteeship toward the shareholders and of public trusteeship toward the patrons of the road is now much more fully recognized.

Which preposition to use with  trusteeship