Search for past "The Baltimore Sun" issues online by visiting its website (www.baltimoresun.com). You may find the exact articles you want without having to purchase the entire issue.
Contact "The Baltimore Sun" directly. Their Archives department offers back issues for a fee and you can contact them online, via telephone or mail.
Check your local library. Many libraries, even outside of Baltimore, have back issues of important national newspapers like "The Baltimore Sun" preserved on microfiche or other archival media.
Use a historical newspaper service. These services specialize in exceptionally old or rare copies of back issues of newspapers. Primarily catering to the academic and research communities, these services have vast archives of a variety of newspapers such as "The Baltimore Sun."