The best-researched, most comprehensive secondary account we have come across is:

Rose, Emily C. "Maximilian D. Berlitz." In Immigrant Entrepreneurship: German-American Business Biographies, 1720 to the Present, vol. 2, edited by William J. Hausman. German Historical Institute. Last modified June 19, 2012. http://www.immigrantentrepreneurship.org/entry.php?rec=22Link opens in a new window

On Berlitz's predecessors, see also Finotti, I. 2010. Lambert Sauveur à l'ombre de Maximilian Berlitz: Les débuts de la méthode directe aux États-Unis , Quaderno 7. Online: http://amsacta.cib.unibo.it/2739/1/Finotti_Quaderno_7.pdfLink opens in a new window

There are also persisting more 'mythical' accounts (e.g. for the 'official 'Berlitz story', see: http://www.berlitz.de/en/berlitz_company/tradition/history/Link opens in a new window), important parts of which have been challenged by Emily Rose's research (cf. Rose, E. 2000. 'The new Berlitz story'. Online: http://www.portraitsofourpast.com/berlitz.htmLink opens in a new window).

Source of photo: Berlitz (UK) Ltd website (uploaded here with permission)

'Between 1881 und 1914, the company experienced huge expansion. More than 200 Berlitz language schools were founded worldwide. The first language school in Europe opened [here] at Leipziger Strasse 123, Berlin, in 1888'. (Source: 'Berlitz Story' - see reference above)

 

Source of photo: Berlitz (UK) Ltd website (uploaded here with permission)

'This poster from France dates back to around 1900' (Source - 'Berlitz Story' - see reference above)