This article takes its content from the book "Shady Characters: The Secret Life of Punctuation, Symbols & Other Typographical Marks" by Keith Houston. The book originated on his website as a series of articles, the "&" ones are:

- The Ampersand, part 1 of 2 (https://shadycharacters.co.uk/2011/06/the-ampersand-part-1-o...)

- The Ampersand, part 2 of 2 (https://shadycharacters.co.uk/2011/06/the-ampersand-part-2-o...)

- The Ampersand, part 2½ of 2 (https://shadycharacters.co.uk/2011/07/the-ampersand-part-2%c...)

I'd highly recommend the website and the book, and also his new book "The Book" about the origin of the book.