Looking for divorce papers from Montana

I am looking for the divorce papers from Montana for my great aunt, Mary J. Brown, who got married the 1st time to Charles (Chas) W. Jackson on the 15th May 1919. The Marriage License lists the county of Musselshell, MT. Also I am searching for the 2nd marriage of my great auntie Mae Brown (spelling of the first name has change) to Elmer H. Martin on 20th December 1924. The Marriage License  lists the county of Stillwater. My great auntie got divorced 1929, because her second husband Elmer H. Martin got remarried to Helen Law on the 7th January 1929. Where will I find the record of official divorce paper or better to say which administration or third party will I have to contact? Enclosed are the Marriage Licenses.For any help for direction I would be grateful. Thanks in advance.