Rewards cards are used for 80% of credit-card purchases, according to a recent study by Phoenix Marketing International, a market research firm.

WSJ: The New Credit-Card Rewards Programs

This Spring the International Journal of Research in Marketing surveyed several academic papers looking at sales productivity and how to enhance it.

FORBES: Is It Possible to Have Too Much Information In Sales?

Ziv Carmon, a professor of marketing at INSEAD, the international business school with campuses in Abu Dhabi, France and Singapore, co-conducted research with Nobel laureate Daniel Kahneman, to determine people's feelings about a line's progression.

WSJ: Find the Best Checkout Line