refseek.com
scientificcommons.org
scirus.com
deepdyve.com
qsensei.com
sciseek.com
vadlo.com
nyas.org
inderscience.com
sciweavers.org
umi.com
researcherid.com
asanet.org
blackwell-synergy.com
researchblogging.org
pubzone.org
nasonline.org
ingentaconnect.com
odysci.com
wolframalpha.com
quertle.info
nextbio.com
askkids.com
yippy.com
factbrowser.com
listingsus.com
oeis.org
galaxy.com
factbites.com
patents.com
northernlight.com
onekey.com
kidsclick.org
find.com
monstercrawler.com
beaucoup.com
priorsmart.com
sweetsearch.com
deepwebtech.com
yolink.com
famhoo.com
vmgo.com
sciencedirect.com
scopus.com
worldwidescience.org
scholaruniverse.com
amacad.org
weblens.org
incywincy.com
dibdabdoo.com