Business Card Research Links:

The economist post is the best and most well written one IMO.

Who invented business cards?

Six famous business cards – from Gaga to Obama

https://www.swallowtailprint.co.uk/news/articles/post/78-a-brief-history-of-business-cards

Global business card etiquette

https://www.economist.com/business/2015/03/12/on-the-cards

The History of Business Cards

http://www.designfloat.com/blog/2012/04/02/history-business-cards/