You must provide two (minimum) or three (maximum) letters from referees on official headed paper. They do not have to follow a template. The only provision is that the referees’ contact details should be clearly typed and contain a business email address and a telephone number. The Referees should have collaborated with the candidates and should be willing to answer queries about them. They should be able to communicate in English or French. One of them should be an academic who has taught or supervised the candidate. Check the required documents here.