Tex. Gov't Code § 552.121

An oral history interview, personal paper, unpublished letter, or organizational record of a nongovernmental entity that was not created or maintained in the conduct of official business of a governmental body and that is held by a private or public archival and manuscript repository for the purpose of historical research is excepted from the requirements of Section 552.021 to the extent that the archival and manuscript repository and the donor of the interview, paper, letter, or record agree to limit disclosure of the item.