90:10 rule

The Psychology Influence of Persuasion

The book was recommended by Joel Spolsky. I like the book. The book is divided into 6 parts (Reciprocation, Commitment and Consistency, Social Proof, Liking, Authority and Scarcity) and it has plenty examples and researches.

Few phrases from the book:
Everything should be made as simple as possible, but not simpler - Albert Einstein

It is easier to resist at the beginning that at the end - Leonardo DA Vinci

Where all thin alike, no one thinks very much - Walter Lippmann

The main work of a trial attorney is to make a jury like his client - Clarence Darrow

The way to love anything is to realize that it might be lost - G.K. Chesterton