Possible Clues:

• Quod ___ demonstrandum
• Quod ___ faciendum
• The 'E' of Q.E.D
• QED center
• The 'E' in Q.E.D
• The 'E' of Q.E.D.
• The 'E' in Q.E.D.
• The "E" in QED
• Middle of QED
• QED middle