The description of Soshimori is found in the first part of the story of the killing of the Yamata no Orochi in the arufumi (an "alternate writing" transmitted by Nihonshoki) No.4 in the section 8 of book 1 of the "Nihonshoki" (Chronicles of Japan).
曾尸茂梨については『日本書紀』卷第一第八段一書第四のヤマタノオロチ退治の前段に記述がある。