sentences:  The characterization of rusalkas as both desirable and treacherous is prevalent in Russia, Ukraine and Belarus, and was emphasized by 19th-century Russian authors.The best-known of the great Czech nationalist composer Antonín Dvořák's operas is "Rusalka".In "Sadko" (), an East Slavic epic, the title character—an adventurer, merchant, and "gusli" musician from Novgorod—lives for some time in the underwater court of the "Sea Tsar" and marries his daughter, Chernava, before finally returning home.