Citing sources you refer to is one of the important parts of writing a research paper, thesis, books, etc. You need to use anyone citation style as recommended or prescribed by the journal publisher. The styles differ from journal to journal and institute to institute.
Following link/sources help you understand citations.
How to cite?
Note: Citation styles differ from journal to journal/ publisher to publisher. Similarly many academic institutes use different citation styles. Some use their own in-house style guide. Please check the citation style being followed by a journal/ publisher/ academic institute before writing/ submitting your research work/ document.
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