Citation Index 
Name Publisher URL Address Details
Elsevier http://www.scopus.com Life Sciences, Health Sciences, Engineering, Physical Sciences and Social Science
Clarivate Analytics ISI Science, Social Science, Art & Humanities
Google https://scholar.google.com Provides a simple way to broadly search for scholarly literature. Search across peer-reviewed papers, theses, books, abstracts and articles, from academic publishers, professional societies, preprint repositories, universities and other scholarly organizations.