Negash S, Sheppard NV, Lambert NM እና Fincham FD ለወቅታዊው ደስታ ከሚያስደስት በኋላ የሽያጭ ዋጋ: የወሲብ ስራ ጥናት እና የቅናሽ ዋጋ ቅናሽ in ጆርናል ኦፍ ዎርክ ሪሰርች, 2015 Aug 25: 1-12.
Negash S, Sheppard NV, uLambert NM kunye neFincham FD Ukurhweba kamva Imiphumo yokuzonwabisa okwangoku: Ukusetyenziswa koonografi nokukhawuleza Ukunciphisa in Umbhalo woPhando loSondo, 2015 Aug 25: 1-12.