If you are not satisfied by the comprehensive information contained within the book Earth Not a Globe, feel free to do the following:
Step 1. Look outside your window
Step 2. Read the FAQ
Step 3. Read the FAQ again
Step 4. Read the book "One hundred proofs the Earth is not a Globe" by William Carpenter
Step 5. Read the back-issues of Flat Earth News Quarterly
Step 6. Read the book "Flatland" by Edwin A. Abbott
Step 7. Read The book "The terrestrial plane" by Frederick H. Cook
Step 8. Read the book "Universal gravitation a universal fake" by Charles S. DeFord
Step 9. Read the book "Does the earth rotate?" by William Edgell
Step 10. Read the book "Earth not a globe: scientifically, geometrically, philosophically demonstrated" by Henry J. Goudey
Step 11. Read the book "The book of light" by Gilbert Johnson
Step 12. Read the book "Unpopular truth against popular error in reference to the shape of the earth." by Charles W. Morse
Step 13. Read the book "A challenge from the earth-flattening society" by Richard A. Proctor
Step 14. Read the book "The Earth: A Plane" by John E. Quinlan
Step 15. Read the book "He knew earth is round, but his proof fell flat" by Robert J Schadewald
Step 16. Read the book "The view from the edge; on the necessity of the flat earth" by John P. Sisk
Step 17. Read the book "Is the earth a whirling globe?" by Carl Albert Smith
Step 18. Read the book "Answers to the common 'proofs' that the earth is a globe" by Chester M. Shippey
Step 19. Read the book "In defense of the square peg." by Irving Wallace
Step 20. Read the book "The shape of the earth; some proofs for the spherical shape of the earth given in astronomical and geographical text-books examined, and shown to be unsound" by Arthur V. White
Step 21. Read the book "The Flat Earth and her moulder" by Ossipoff H. Woofson
Step 22. Come to the conclusion of a Flat Earth
100 proofs written in 1881
Flatland written in 1884
Does the earth rotate? written in 1919
Universal gravitation a universal fake in 1931
Earth not a globe written in 1930
The book of light written in 1890
Unpopular truth against popular error in reference to the shape of the earth written in 1913
A challenge from the earth-flattening society written in 1883
The Earth: A Plane witten in 1906
He knew earth is round, but his proof fell flat written in 1973
The view from the edge; on the necessity of the flat earth writtin in 1979
Is the earth a whirling globe written in 1918
Answers to the common 'proofs' that the earth is a globe written in 1930
In defense of the square peg. written in 1957
The shape of the earth; some proofs for the spherical shape of the earth given in astronomical and geographical text-books examined, and shown to be unsound. written in 1909
The Flat Earth and her moulder writtin in 1884
Only two of those books come after space travel... SHUT THE HELL UP