Stephen Spender published a significant number of books, encompassing poetry, essays, biographies, and autobiographical works. It's challenging to provide an exact number as some works were published in different editions or revised over time. However, a good estimate would be
over 30 books.
This includes his major poetry collections like "Twenty Poems" and "The Still Centre," as well as prose works such as "The Destructive Element" and "World Within World."
To get a more comprehensive list, you can consult online databases like Goodreads or the Library of Congress.