Complex sentence: In 1925, Cerf formed a partnership with his friend Donald Klopfer; the two bought the rights to the Modern Library from Boni and Liveright and went into business for themselves.
Split into simpler sentences: In 1925, Cerf formed a partnership with his friend Donald Klopfer. The two bought the rights to the Modern Library from Boni and Liveright and went into business for themselves.