1952, Roger Vee, Vivian Voss, The story of No. 1 Squadron S.A.A.F., sometime known as the Billy Boys[1], page 177:
Major Peter had the qualities making for a great leader of a Fighter Squadron, utter sincerity of purpose, high personal courage, and those general attributes of air-leadership consolidated in the pilot’s word, “cluefulness”
2002, Jon Orwant, “Foreword”, in Computer science & Perl programming[2], →ISBN, page xi:
Jon used to complain that not enough people wanted towrite these: “All the clueful writers want to write about stuff that displays their cluefulness,” he once told me.
2006, Eric Sink on the Business of Software, “Career Calculus”, in Eric Sink[3], →ISBN, pages 124–5:
G is Gifting. It is defined as the amount of natural clufulness you were given “at the factoty.”¶ L is Learning. It is defined as the rate at which you gain (or lose) clufulness over time
2006, William Von Hagen, The definitive guide to GCC[4], →ISBN, page 254:
In a rare burst of clufulness, U.S. export regulations were relaxed so that the DES cryptographic functions could be incorporated into the base GNU C library distribution without sending anyone to jail.