
Source: If: A Father's Advice to His Son
"Introduction"
Please Don't Eat the Daisies (1957)
Source: If: A Father's Advice to His Son
“When you've exhausted all possibilities, remember this: You Haven't!”
Not located in Edison's writings, but found in Robert H. Schuller's self-help book Tough Times Never Last, But Tough People Do! from 1983 https://books.google.com/books?id=8oTOa4n3k4oC&pg=PA28&dq=%22exhausted+all+possibilities%22+remember&hl=en&sa=X&ved=0ahUKEwiL88bb6-vKAhVD-mMKHVzNDVEQ6AEIHTAA#v=onepage&q=%22exhausted%20all%20possibilities%20remember%20this%22&f=false.
Disputed
Source: https://www.facebook.com/photo.php?fbid=346794326803029&set=pb.100044173926915.-2207520000.&type=3