The Google ngram viewer creates charts of the usage of words in books over time. Here we’re just looking from the year 1800 to 2000.
What’s more popularly written about over time? Here’s what the chart says:
#1. Sales and Selling
#2. Advertising
#3. Marketing
#4. Public Relations
Surprising results? I see more discussions about PR and marketing in social media than I do about sales or advertising- but maybe the people interested in the latter two subjects are less interested in discussing things in social media. What books are written is more driven by what people will actually pay for. Historically, profits are more associated with selling than marketing or PR, so that’s one clear reason people would have more money available for books about sales.
According to Google, what people are searching for online is slightly different…

Marketing and advertising switch places. And if you do the same search for sales book vs marketing book etc., the results are at about the same proportion.
By the way, SEO and Google barely show on the historical chart. A funny one is the little blip we get about The Internet in the next chart (I’d love to see a comparison of the number of websites and webpages to number of published books).

