How can I find magazines and/or newspapers that were published before 1906?
These UI Libraries' resources should be helpful:
The Times Digital Archive, 1785-1985 http://purl.lib.uiowa.edu/timesda
Use the advanced search to limit by date (before 1906) and limit to display advertising. Search for terms like: codeine or heroin or opium
Early American Newspapers http://proxy.lib.uiowa.edu/login?url=http://infoweb.newsbank.com/?db=EANA&s_startsearch=keyword
Use the Era tab to limit by date; use the article tab to limit to advertisements; enter search terms
19th Century Historica United States Newspapers http://purl.lib.uiowa.edu/19cusn
Limit by advertising and date