Per Debra's comment - https://familyhistory.bdm.nsw.gov.au/lifelink/familyhistory/search - Death - CAMPBELL, JOHN D - NSW BDM 5795/1910 - F = JOHN, M = MARY - KOGARAH. Ryerson Index may give you a lead to Trove which may have more details. FamilySearch also worth a look as they have extensive free document bank. Cheers Neil