The book is 'The Ethnographic Interview' by James P. Spradley, published in 1979.
For those facilitating knowledge retention or transfer in organisations, the techniques that Spradley describes are ideal for eliciting valuable knowledge in an interview situation. They are grounded in extensive research and are still absolutely relevant and pragmatic. Despite being written by an academic, the text is very accessible, full of examples and clearly relevant for the practitioner.
For knowledge retention and transfer, the imperative is how is the knowledge that is elicited is put to use, who needs it and how it is accessed (format and channel). This means making the knowledge transfer process an integral part of the discovery stage - this is quite different to pure ethnographic study, where the analysis happens much later. Another major difference in producing explicit knowledge for the purpose knowledge transfer is that the outputs (knowledge assets) are for the benefit of knowledge recipients not the facilitator (or ethnographer).
I highly recommend the book, but for those pushed for time, or unwilling to invest £50 for a paperback, I have written a synopsis and extracted the most relevant tips and techniques. KIN members can see the synopsis on KIN Memberspace in the Knowledge Retention and Transfer SIG library.