Conducting Interviews allow researchers to learn detailed information from individuals. It is useful when you want to learn more about indivduals who experience something first hand first or talk to someone knowledgeable about a topic. There are several different types of interviews including: face to face, phone, email, and chat.
Catching stories: A practical guide to oral history by 
Handbook of interview research: Context & method by 
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The moderator's survival guide: Handling common, tricky, and sticky situations in user research by 
Oral History: Understanding Qualitative Research by 
Qualitative interviewing: The art of hearing data by 
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Research interviewing: The range of techniques by 