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, Lambert NM ndi Fincham FD Kugulitsa Pambuyo Panthawi Zokondweretsa: Zithunzi Zolaula Kugwiritsa Ntchito ndi Kutaya Nthawi Yopatsa in Journal of Research Research, 2015 Aug 25: 1-12.