A list from Amazon, link here.
The first economics textbook on the list is Mankiw’s Principles of Microeconomics.
The first 10 on the list:
Rank ISBN Title Publisher Primary Author Year 1 890420254 Diagnostic and Statistical Manual of Mental Disorders DSM-IV-TR Fourth Edition (Text Revision) Amer Psychiatric Pub American Psychiatric Association 2000 2 321558235 Campbell Biology (9th Edition) Benjamin Cummings Jane B. Reece 2010 3 1433805618 Publication Manual of the American Psychological Association, Sixth Edition Amer Psychological Assn Amer Psychological Assn 2009 4 1429215976 Psychology Worth Publishers David G. Myers 2009 5 538453044 Principles of Microeconomics South-Western College Pub Mankiw 2011 6 78111005 Managerial Accounting McGraw-Hill/Irwin Ray Garrison 2011 7 73511706 Understanding Business McGraw-Hill/Irwin William Nickels 2009 8 321694155 Human Anatomy & Physiology with MasteringA&P (8th Edition) Benjamin Cummings Elaine N. Marieb 2010 9 132109174 Cost Accounting (14th Edition) Prentice Hall Charles T. Horngren 2011 10 77306295 The Art of Public Speaking with Connect Lucas McGraw-Hill Stephen Lucas 2008