The Slavic languages have the name which is rendered as Sviatopolk in Russian, Świętopełk in Polish and Svatopluk/Svätopluk in Czech and Slovakian.
Świętopełk is only named in the chronicles of Thietmar of Merseburg; he was omitted in the document "Dagome iudex" (ca. 991/92), were are named his parents and full-brothers Mieszko and Lambert, a fact who indicated that he maybe was dead by that time, in or before 991.