Which preposition to use with unavailable

for Occurrences 4%

"I'm afraid we cannot use your story, Mr. Clark," she said gently, and remembering the formula that usually accompanied her own rejected manuscripts she added: "This does not necessarily imply a lack of merit in your contribution, but is due to the fact that it is at present unavailable for our use.

to Occurrences 3%

All the intervening ground was at first sight unavailable to one who wished to plant an ambuscade, because it not only had not any part that was woody, but none even covered with brambles, but in reality formed by nature to cover an ambush, so much the more, because no such deception could be apprehended in a naked valley and there were in its curvatures hollow rocks, such that some of them were capable of containing two hundred armed men.

Which preposition to use with  unavailable