From Conrad Knickerbocker’s interview of William S. Burroughs in “The Art of Fiction No. 36” (The Paris Review: Fall 1965, No. 35):
For exercise, when I make a trip, such as from Tangier to Gibraltar, I will record this in three columns in a notebook I always take with me. One column will contain simply an account of the trip, what happened. I arrived at the air terminal, what was said by the clerks, what I overheard on the plane, what hotel I checked into. The next column presents my memories; that is, what I was thinking of at the time, the memories that were activated by my encounters; and the third column, which I call my reading column, gives quotations from any book that I take with me. I have practically a whole novel alone on my trips to Gibraltar.