Pring CM, Skelding-Millar L, Goodall RJ. Expectant treatment or cholecystectomy after endoscopic retrograde cholangiopancreatography for choledocholithiasis in patients over 80 years old? Surg Endosc. 2005 Mar;19(3):357-60.
Finkelstein EA, Kosa KM. Use of incentives to motivate healthy behaviors among employees. Gender issues. 2003 Jun;21(3):50-9. doi: 10.1007/s12147-003-0005-0