Learning about applicable sources is a key part of understanding the problem. While the four sources mentioned are good ones to use, some may be preferable to others. What record to use first is dependent upon what information has already been obtained. In this case, since the exact date of death and place of burial appear to be unknown, our initial search options may be more limited. Searching for an unindexed obituary for the entire year of 1913 is time consuming.
Death certificates are most likely in some alphabetical format, facilitating a search.
The certificate hopefully will provide the date of death and probably the cemetery of burial, thus simplifying research in those records. Of course if there are no death records, the search procedure would have to be altered. This is why it is necessary to learn about available records in the locale and time period being researched. After all, not all death records are indexed, and in some areas obituary indexes exist. Learning about the sources for your area will significantly impact how you research using the information you already have.