I write and speak  about the advertising industry in the history of radio and television, particularly the role of ad agencies in creating radio and television programs and how the ad industry helped shape commercial broadcasting  from the 1920s through the 1960s.
For example, J. Walter Thompson employees produced, scripted, scored, and directed Kraft Music Hall starring Bing Crosby. Young & Rubicam produced the Jack Benny show for General Foods. BBDO oversaw General Electric Theater. Benton & Bowles produced The Andy Griffith Show for General Foods. 
The programs were advertising vehicles, what today we might call  "branded content."  Rather than ads, entertainment shaped the brand image, as when Jack Benny joked about his sponsor Jell-O on his 1930s radio comedy show, or when cheese recipes were demonstrated between scenes of the 1950s live drama anthology Kraft Television Theater. Today we see influencers pitching vitamins on social media.
Areas of expertise include 1950s-60s television; "old time radio" (1930s-40s); 20th c advertising; ad agencies (JWT, BBDO, B&B, Y&R, FCB, Ted Bates, McCann-Erickson); 1940s-50s broadcast blacklisting; the Creative Revolution; LSD and drugs in 1960s advertising agencies; docudramas; news dramatizations; anthology dramas; soap operas; family vloggers;  sponsorship; influencers; tv commercials; streaming television; the Kardashians;  Ozzie Nelson & family;  integrated advertising; and branded entertainment.
I research companies such as  Kodak, Kraft, Wrigley, Time, DuPont, General Motors, General Electric, Armstrong Cork, US Steel, Coca-Cola, Pepsi, and AT&T.

I post old ads at wordfromoursponsor on Tumblr.