The Case—Please Hear Me Out—Against the Em Dash –
http://www.slate.com/id/2295413/
Shady Characters – The Secret Life of Punctuation –
http://www.shadycharacters.co.uk/
The Correct Use of ‘Had’ (Past Perfect Tense) http://learnenglish.britishcouncil.org/en/grammar-reference/past-perfect