Clinicaltrials.gov (U.S.A National Library of Medicine).http://clinicaltrials.gov
ISRCTN. International Standard Randomized Controlled Trial Number Register. http://www.controlled-trials.com/isrctn/
Brazilian Clinical Trials Registry (ReBec).http://www.ensaiosclinicos.gov.br/
Australian New Zealand Clinical Trials Registry (ANZCTR).http://www.anzctr.org.au/
The Netherlands National Trial Register (NTR). http://www.trialregister.nl
UMIN Clinical Trials Register-Japón.http://www.umin.ac.jp/ctr/
Chinese Clinical Trial Registry (ChiCTR).http://www.chictr.org/
Clinical Research Information Service (CRiS), Republic of Korea.http://ncrc.cdc.go.kr/cris/index.jsp
Clinical Trials Registry - India (CTRI).http://www.ctri.in/
EU Clinical Trials Register (EU-CTR).https://www.clinicaltrialsregister.eu/
German Clinical Trials Register (DRKS).http://www.germanctr.de/
Pan African Clinical Trial Registry (PACTR).http://www.pactr.org/
Sri Lanka Clinical Trials Registry (SLCTR).http://www.slctr.lk/
Iranian Registry of Clinical Trials (IRCT).http://www.irct.ir/
Thai Clinical Trial Registry (TCTR).http://www.clinicaltrials.in.th/
Peruvian Clinical Trial Registry (REPEC).http://https://ensayosclinicos-repec.ins.gob.pe/en/
Lebanese Clinical Trials Registry (LBCTR).http://lbctr.emro.who.int/