Complex sentence: Sadko (the name of the main character) is an opera in seven scenes by Nikolai Rimsky-Korsakov to a Russian libretto by the composer with assistance from Vladimir Belsky, Vladimir Stasov, and others.
Split into simpler sentences: Sadko (the name of the main character) is an opera in seven scenes by Nikolai Rimsky-Korsakov. The libretto was written by the composer, with assistance from Vladimir Belsky, Vladimir Stasov, and others.