?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adissertation&rft.aulast=Al-Zubaidi&rft.aufirst=Abdulgawi+Salim.&rft.au=Al-Zubaidi%2C+Abdulgawi+Salim.&rft.tpages=402&rft.title=Experiments+on+Yemeni+children's+understanding+of+class+inclusion+measurement+and+number+conservation&rft.degree=Doctoral&rft.date=1987&rft.inst=Institute+of+Education%2C+University+of+London