Google will find lots of links to The Harvard System of Referencing, and your uni's library will probably have a handout explaining the various styles in depth.
The trick with an interview conducted by you (and is not published elsewhere) is that it is a "personal communication" and the Harvard System treats these differently to all other references:
TEXT
Joe Average said "cheese twisties taste heaps better than chicken" (personal communication, January 1, 2004).
There is no entry in the Reference section of your paper to the personal communication.
[BTW, your school might prefer the date in a non-US format, even if using the Harvard System.]
[Also, personal communications are not "peer reviewed works", so you can't use them to support a statement of fact, as in "the earth is flat (Hawkings, personal communication, January 1, 2004)". They are fine for statements of opinion, as in "Hawkings believes that the earth is flat (personal communication, January 1, 2004)".]
In principle, pamphlets are no different to books. In practice, pamphlets are what librarians call "ephemera", that is, of the moment. So they tend to have incomplete publishing details (eg, the author, date, etc) and tend to be difficult for other researchers to find in later years. So you owe it to the reader to provide the fullest reference possible, using whatever information there is.
If you don't know the author, use the name of the issuing organisation instead. If you don't know the date, some people use the abbreviation (n.d.). Unlike a book, where you can assume the publisher's address can be found in later years, it would be a nice for future researchers if you gave the address if you know it.
TEXT
The Cheese Twisty Rulz Collective states "Chicken Twisties are the Devil's work" (CTRC).
REFERENCE
Cheese Twisties Rulz Collective (n.d) Down with Chicken Twisties. Cheese Twisties Rulz Collective, Adelaide.
Don't get too hung up on the format of references. The real trick when writing a paper is to keep a good note of what you read and what it contained so that you don't have to go and re-read the books just to do the referencing.
Best of luck in your studies,
Glen (a researcher)