Complex sentence: Ludwig van Beethoven's Cello Sonata No.3 in A major, Op.69 was written in 1808, Beethoven's most productive compositional period.
Split into simpler sentences: Ludwig van Beethoven's Cello Sonata No.3 in A major, Op.69 was written in 1808. The Sonata No.3 dates from Beethoven's most productive compositional period.