The fourth edition of the famous Harold van der Heijden endgame study database (HHdbIV) is available now. The new edition not only has more than eight thousand extra studies, but also the solutions of tens of thousands of studies were corrected or updated. It is by far the most comprehensive collection of endgame studies available.
The previous editions from 1991, 2000 and 2005 contained 23358, 58801, and 67691 endgame studies respectively. The new version has no less than 76,132 endgame studies. When you would undertake to play through all the studies at a rate of 3 minutes per study for 3 hours EVERY day, it would cost you three and a half years to accomplish that task!