COBISS

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arXiv

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Bentham Open

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BioMed Central

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ChemlDplus

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Dart – Europe E-theses Portal

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DOAJ – Directory of Open Access Journals

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DoiSerbia

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DOAR – Directory of Open Access Repositories

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Electronic Journals Library

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ERIC- Education Resources Information Center

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ETHOS – E-theses online service

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FreeMedical Journals

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Google Scholar

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HRČAK – Portal hrvatskih znanstvenih časopisa

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OpenThesis

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PubMed Central (PMC)

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ROAD – Directory of Open Access Scholarity Resources

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USPTO – United States Patent and Trademark Office