Martindale is about 4 miles SE of San Marcos, TX, just a mile or so inside the Caldwell County northwest line. You could go to the Caldwell County tax collector's office in Lockhart,TX and look through early 1900s tax records (if they still have them). This would probably give you some idea of the specific location of his land. Otherwise, you can go to the County clerk's office where all deeds are filed, and search land title records for Refugio Olguin's name and deed file reference when he bought, or sold, land in the county. A xerox copy of the deed complete with exact location and description of the land can be purchased. The deed might mention the cemetery. If not, you could then stay with the deed book records and track the land ownership forward to the present owner, and contact him/her personally to ask of they know of a cemetery on their property. The local abstract office could do this much quicker than you, but it could cost you $200-300 for the service.