Complex sentence: In 1926 he published "Oblicza zmyślone", his first book of poems and his first set of poems for children "Tańcowała igła z nitką" was published in 1937.
Split into simpler sentences: In 1926 he published "Oblicza zmyślone", his first book of poems. His first set of poems for children "Tańcowała igła z nitką" was published in 1937.