The custodian may make public records available for inspection or copying, or both, by an applicant without a written request except as set forth below. Written requests shall be required in all instances when the public records requested may contain information relating to any of the following: Adoption records; Welfare records; Letters of reference; Circulation records; Gifts; Retirement records; Personnel records; Hospital records; Student records; Medical and psychological information; Sociological information; Commercial information; Public employee information; Financial information; Security of an information system; Licensing records; Interagency and intra-agency documents; Examinations; Research projects; Appraisals of real property; Information concerning investigations; Information which may cause substantial injury to the public interest; Privileged or confidential information; or Information protected by state or federal law, court rule, or court order. A custodian may require a written request for other public records if in the custodian's discretion the request will facilitate the response to the request for records.