There is a Robert A. Jones who died in November 1959 buried in Greenhill Cemetery in Muskogee, Oklahoma. You can find additional information here:
http://www.usgennet.org/usa/ok/county/muskogee/cemeteries/gr...Death certificates in Oklahoma are issued by the state's vital records office and you can write to it and send the appropriate fee for same. Do a search online for the address and cost.
Good luck.
Myra