↑ Pettigrew, Jane (2004). The Tea Companion: A Connoisseur's Guide (Connoisseur's Guides). Philadelphia, Pa: Running Press Book Publishers. ISBN 0-7624-2150-9.
↑ Fenix, Micky (24 July 2008). "More Than Just A Pot Of Tea". Philippine Daily Inquirer. Archived from the originalon 20 January 2013. Stephen Twining traced back his family's business to the 1700s, when coffee houses as meeting places were the vogue. How ironic that it was in the company's coffee house where tea was introduced. Earl Grey tea makes Stephen Twining wish he could move back time because the company did not lay claim to the formula, or the name, when they had produced the blend for the British Prime Minister who was known as the second Earl Grey.
↑ Pagano, Margareta (3 July 1985). "The secret of Earl Grey tea is changing hands at last / Sale of Jacksons of Piccadilly to Fitch Lovell food manufacturing group". The Guardian (London). The original secret formula for Earl Grey tea is changing hands after 155 years with its sole proprietors, the Jacksons of Piccadilly tea merchants... with the sale goes the special recipe of the Earl Grey blend which was entrusted to Robert Jackson's partner, George Charlton, in 1830 by the second Earl Grey. To this day the formula—which mixes black China tea with other unknown teas—has remained unaltered.
↑ RFLP ANALYSIS OF THE ORIGIN OF CITRUS BERGAMIA, CITRUS JAMBHIRI, AND CITRUS LIMONIA. nternational Society for Horticultural Science. Retrieved 18 February2012.
