Complex sentence: Silberer freely quotes other psychologists in Problems of Mysticism and its Symbolism such as Freud and Jung and identifies earlier studies in Alchemy-such as that of the 19th century writers Ethan Allen Hitchcock and N Landur-as opening the way for his explorations.
Split into simpler sentences: Silberer freely quotes other psychologists in "Problems of Mysticism and its Symbolism", such as Freud and Jung. He identifies earlier studies in alchemy, such as those of the 19th century writers Ethan Allen Hitchcock and N. Landur, as opening the way for his explorations.