Complex sentence: In 1972, Allen wrote with Larry Abraham "None Dare Call It Conspiracy" (prefaced by Congressmen John G. Schmitz), a best seller which achieved sales of over five million copies worldwide during the United States presidential election.
Split into simpler sentences: In 1972, Allen wrote with Larry Abraham "None Dare Call It Conspiracy" (prefaced by Congressmen John G. Schmitz), a best seller. It achieved sales of over five million copies worldwide during the United States presidential election.