Explanation and Answer:
A text writer can avoid plagiarism only in the case when he/she keeps records of all the sources to which he/she is referenced. If the author of the source that is used, does not stated, it is also a plagiarism. If sources that are similar to his or her own ideas are avoided and quotes from these sources are avoided, it can only contribute to gaining the impression that it tries to avoid plagiarism, on the contrary, it is necessary to quote similar sources as a confirmation of one's own attitude, with the consistent monitoring of its original and authentic idea.
Franklin roosevelt because he was an american president at the time