He wrote about twenty books, most of them are not published anymore.
Then he wrote about five books and he had such a natural style.
He has written about 22 other books (as of 2004).
He has written about fifteen books, two are major textbooks.
He wrote about 67 books which were adopted as textbooks for high schools and colleges.
By 1988, he had written about 120 books and 500 articles.
He has written about 80 books in several subjects.
Wallace wrote about 22 books, depending on how one counts them.
The modern world owes much to this early researcher, who wrote about 180 books.
He has written about a dozen books in roughly as many years.