Express the reference details for each

in the Harvard style method and list them in alphabetical order in a reference list

Harvard style method is one of the various ways in referencing a source or a credible reference. It includes format and style in writing, some basic rules and simple procedures.

An example for an APA is

APA:

According to Mandela (2010), in politics many of the individuals who work in these offices or fields experience insistent and pragmatic obstacles, and because of this, many are sleep deprived and are impeded with self-guiding introspection. Thus, the outcomes involving such behaviors only contribute to many of these politicians', bound to exhibit such errors, these errors then are inevitable for most of these individuals. Although, some sectors like the armchair politicians are the only ones protected if errors are done. But other politicians are bound to answer cases.

Reference: Conversation with myself by Nelson Mandela. p. 35. London: Macmillan, 2010