itself to five Norse male names and one female name, of which the most popular ones would be Oleg, Igor and Gleb (was murdered in 1015 and canonized). The name Rurik (Hrœrekr) reappears in the mid-11th c. but stays restricted in use. Among female names, only Olga stays popular. The Norse names Hákon, Óleifr, and Ivarr remain in use among the East Slavic nobility, but Norse names become rarer at the end of the 10th c. which may point to increased assimilation of the Rus into the Slavic population. Among the Norse names that are not used in the ruling family, there is great variation in how they are spelled in the treaties. All names except for Oleg, Olga and Igor are spelled as closely to Old Norse as was possible in Old East Slavic. There were also variations in how the vowels were presented Óleifr was shown as Oleb or Uleb, Hákon as Jakun and Akun, Arnfastr as Arfast and Fastr as Fost. The interdentals /þ/ and /ð/ are rendered as d, but also rarely as z or t as in Turd from Þórðr and in Vuzlev from Guðleifr. The Fr- in the beginning of names which was common in Old Norse but rare in Old East Slavic usually appeared as Pr- as in Prasten from Freysteinn. There was no standard way of spelling ON names. While the Primary Chronicle uses the same Slavicized forms throughout, rendering Helgi as , Helga as Ol'ga, Ingvarr as Igor' and Guðleifr as Gleb, they are unlikely to represent the form the names had at the end of the 10th c. Foreign sources give forms closer to the Old Norse originals. Byzantine sources from the second half of the 10th c. preserve the nasalization in Ingvarr, and in the Cambridge document written in Hebrew, Helgi appears as HLGW, with initial H-. The adaptation of Guðleifr was still not complete by 1073, as shown in a manuscript where there is a vowel between G- and -l- in Gleb, showing that the name is still pronounced with an initial Gu-. Theses sources reflect authentic Old Norse pronunciation of these names, which shows that the adaptation of these names did not take place in the 10th c. but was finished a century later. When the Primary Chronicle was written in 1113, the annalist used the already fully adapted Old East Slavic forms and he does not