20890 contract law/ authenticated contract/ contesting signature contract law Federal supreme court of Ethiopia cassation decisions authentication and registration of documents volume 5 contract law authenticated contract contesting signature በባለስልጣን ፊት በተረጋገጡ ሰነዶች ላይ ያሉትን ፊርማዎችና የሰነዶቹን ይዘት ማስተባበል ስላለመቻሉ Cassation Decision no. 20890
