I think sir, since you care for the advice of an old man, sir, you will find it a very good practise, always to verify your references, sir!

Advice given to Dean John William Burgon, (29 November 1847), in response to the question: "Every studious man, in the course of a long and thoughtful life, has had occasion to experience the special value of some one axiom or precept. Would you mind giving me the benefit of such a word of advice?"; quoted in Lives of twelve good men, by John William Burgon, 1888, vol. 1 p. 73.