journals.cambridge.org
.nature.com
.opticsinfobase.org
.symposium-journals.co.uk
.journals.uchicago.edu
.symposium-journals.co.uk
.royalsocietypublishing.org
.aps.org
.tesisenred.net
.loc.gov
.lamjol.info
.aip.org
.blackwell-synergy.com
.euppublishing.com
.ingentaconnect.com
.liebertonline.com
.lyellcollection.org
.palgrave-journals.com
.rsc.org
.scirus.com
agris.fao.org 
asae.frymulti.com
highwire.stanford.edu
journals.pepublishing.com
online.sagepub.com
.ncbi.nlm.nih.gov
static.pubmed.gov
.ebrary.com
.ebscohost.com
.ebsco-content.com
springerlink.com
.scielo.org
.scielo.br