Since this sans-serif typeface was developed in 1957 by Swiss designer Max Miedinger, Helvetica has grown in popularity, appearing everywhere from signage in the New York City Subway system to advertising for Toyota, American Airlines and Panasonic.
Most of you probably used Excel or a similar spreadsheet software. If columns are set to be labeled by letters after Z goes AA. And then AB,... AZ, BA,... etc. But when it comes to old books, there were other ways to use letters for sorting.