Question: What medical job did the best-selling author with between 20 million and 30 million copies sold of Who Moved My Cheese hold ?

text: List of best-selling books
List of best-selling individual books -- Between 20 million and 30 million copies

This page provides lists of best-selling individual books and book series to date and in any language. Best selling refers to the estimated number of copies sold of each book, rather than the number of books printed or currently owned. Comics and textbooks are not included in this list. The books are listed according to the highest sales estimate as reported in reliable, independent sources. This list is incomplete because there are many books, such as The Count of Monte Cristo by Alexandre Dumas, or A Christmas Carol by Charles Dickens, that are commonly cited as best-selling books yet have no reliable sales figures. Similarly, many notable book series that sold very widely are poorly documented (Land of Oz) or consist of multiple sub-series (Tom Swift). According to Guinness World Records as of 1995, the Bible is the best-selling book of all time, with an estimated 5 billion copies sold and distributed. The Quotations from Chairman Mao Tse-tung, also known as the Little Red Book, has produced a wide array of sales and distribution figures - with estimates ranging from 800 million to over 6.5 billion printed volumes, with some claiming the distribution ran into the billions and some citing over a billion official volumes between 1966 and 1969 alone as well as untold numbers of unofficial local reprints and unofficial translations. Exact print figures for these and other books may also be missing or unreliable since these kinds of books may be produced by many different and unrelated publishers, in some cases over many centuries. All books of a religious, ideological, philosophical or political nature have thus been excluded from the below lists of best-selling books for these reasons. Having sold more than 500 million copies worldwide, Harry Potter by J. K. Rowling is the best-selling book series in history. The first novel in the series, Harry Potter and the Sorcerer's Stone, has sold in excess of 120 million copies, making it one of the best-selling books of all time.
Book Author ( s ) Original language First published Approximate sales
The Hunger Games Suzanne Collins English 2008 29 million in U.S
The Young Guard ( Молодая гвардия ) Alexander Alexandrovich Fadeyev Russian 1945 26 million copies in USSR
Who Moved My Cheese ? Spencer Johnson English 1998 26 million
Paul et Virginie Jacques-Henri Bernardin de Saint-Pierre French 1788 25 million
Lust for Life Irving Stone English 1934 25 million
The Wind in the Willows Kenneth Grahame English 1908 25 million
The 7 Habits of Highly Effective People Stephen R. Covey English 1989 25 million
Virgin Soil Upturned ( Поднятая целина ) Mikhail Sholokhov Russian 1935 24 million copies in USSR
The Celestine Prophecy James Redfield English 1993 23 million
The Fault in Our Stars John Green English 2012 23 million
The Shack William P. Young English 2007 22 million
Uncle Styopa ( Дядя Степа ) Sergey Mikhalkov Russian 1936 21 million copies in USSR
The Godfather Mario Puzo English 1969 21 million
Love Story Erich Segal English 1970 21 million
Catching Fire Suzanne Collins English 2009 21 million in U.S
Mockingjay Suzanne Collins English 2010 20 million in U.S
Autobiography of a Yogi Paramahansa Yogananda Hindi 1946 20 million < https : //www.anandala.org/autobiography-of-a-yogi/ >
Gone Girl Gillian Flynn English 2012 20 million
The Girl on the Train Paula Hawkins English 2015 20 million
All Quiet on the Western Front ( Im Westen nichts Neues ) Erich Maria Remarque German 1929 20 million