中国科学技术信息研究所--国家工程技术数字图书馆

georgetown university.(4)

university of california davis.(4)

university of southern california.(4)

harvard university.(3)

oklahoma state university.(3)

the chinese university of hong kong (hong kong).(3)

the pennsylvania state university.(3)

university of illinois at urbana-champaign.(3)

columbia university.(2)

cornell university.(2)

michigan state university.(2)

oregon state university.(2)

princeton university.(2)

the university of north carolina at chapel hill.(2)

the university of wisconsin - madison(2)

the university of wisconsin - madison.(2)

university of california berkeley.(2)

university of california los angeles.(2)

university of michigan(2)

carnegie mellon university.(1)

chicago state university.(1)

colorado state university.(1)

duke university.(1)

howard university.(1)

indiana university.(1)

iowa state university.(1)

kent state university.(1)

kwara state university (nigeria)(1)

marmara universitesi (turkey).(1)

michigan state university(1)