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Life of Samuel Johnson (1791), Vol II
                                    
"A Third Kind of Knowledge" http://www.edge.org/q2010/q10_7.html#saffo, in The Edge Annual Question—2010: How Is the Internet Changing the Way You Think? http://www.edge.org/q2010/q10_index.html, January 2010
                                        
                                        April 18, 1775, p. 258 
Life of Samuel Johnson (1791), Vol II
                                    
Source: Four Seasons in Rome: On Twins, Insomnia, and the Biggest Funeral in the History of the World
                                        
                                        The first two sentences of this statement first appear as attributed to France in the 1990s, but the full statement is earlier attributed to William Feather, as quoted in  Telephony, Vol. 150 (1956), p. 23 http://books.google.com/books?id=Wm0jAQAAMAAJ&q=%22being+able+to+differentiate+between+what+you+do+know%22&dq=%22being+able+to+differentiate+between+what+you+do+know%22&hl=en&sa=X&ei=qYJOU9dAzoXRAYumgcAP&ved=0CMsCEOgBMDQ 
Misattributed
                                    
As quoted in Telephony, Vol. 150 (1956), p. 23 http://books.google.com/books?id=Wm0jAQAAMAAJ&q=%22being+able+to+differentiate+between+what+you+do+know%22&dq=%22being+able+to+differentiate+between+what+you+do+know%22&hl=en&sa=X&ei=qYJOU9dAzoXRAYumgcAP&ved=0CMsCEOgBMDQ; the first two sentences of this statement began to be attributed to Anatole France in the 1990s, but without any citations of sources.
Source: The Boy Book: A Study of Habits and Behaviors, Plus Techniques for Taming Them
Source: Twitter post https://twitter.com/RoKhanna/status/1078458258833268736 (28 December 2018)
1974 speech, in Voices of Multicultural America: Notable Speeches Delivered by African, Asian, Hispanic and Native Americans, 1790-1995 by Deborah Gillan Straub
Interview in First for Women magazine (February 8, 2010, p. 46) http://jennifer-beals.com/media/press/first.html.
 
                            
                        
                        
                         
                            
                        
                        
                         
                            
                        
                        
                         
                            
                        
                        
                        