We spend a lot of time discussing sources here on WT for obvious reasons and after we have learned how to cite them, the biggest challenge can be finding them. Here is a reminder not to overlook cemeteries. I am not just referring to Find-A-Grave, taking photos or grave marker transcription and rubbing. Don't forget to also inquire at the cemetery office.
Formerly, I was in the cemetery and funeral business. Not all family folders were full, but certainly the more documentation we had on an interred family member, the better we were able to assist those that called or stopped by. The available records and information can include death certificates, death notices and obits, cemetery maps, detailed plot location and the cemetery system of sections, lots and grave numbering. If the deceased was a veteran, there may be a DD-214 (the government one page discharge from service document) which is required at US National Cemeteries. There may also be multiple deceased family members buried around the relative you are researching or in other sections of the cemetery and their records may be in other folders. Further, the administrator and/or sales staff may keep family contact information on file.
I worked for corporations that owned numerous large cemeteries so all of the locations had an office. I realize though, that many cemeteries not only don't have an office, far too many do not have a listed telephone number. Tragically, there are countless abandoned cemeteries where the interred are long forgotten. Cemeteries without an on-site office may be managed by a private company, a church, a city or a township and you will need to call to find out where they keep the records. Here is the Global Cemeteries Project and US Cemeteries Project of WikiTree. Here is an applicable page on cemeteries from GenealogyBuff.com. If you are going to be at the cemetery anyway, my tip is to Check the Office!
Stay on the trail
Rod