Express Your Thoughts
Select good reference books by authors who have extensively worked on the subject, read and understand the concept before you start writing your dissertation. You cannot get away from plagiarism by merely rephrasing the sentences and claiming it your work. Moreover, when you rephrase, there is a risk of misrepresentation of the concept. Thus, the best way to avoid plagiarism is to grasp the idea and summarize in your words.
Maintain a Bibliography
The bibliography is the list of books and other scholarly articles referred while writing any assignment. While you are collecting the material for your dissertation, remember to collect the name of books along with details like author, year of publication, chapter number or chapter name as well as title of the article. Different institutes have different standards for maintaining the bibliography, read properly the instruction before you start writing.
Quotation and Citation of Others Work
If you have to use the exact word of another author or even your own work, use quotation marks. While quoting, make sure to use the exact same words and give the due credit to the author by citing the source as specified by your institution. Try to avoid quoting too many sentences, it is best to keep the quotes within 40 words. As many evaluators don't prefer quotation.
Apart from these indigenous methods you can check your content for originality from the online plagiarism checker like http://smallseotools.com/plagiarism-checker/ or use paid service a complete package from plagiarismremoval.in/ and many more.