A paragraph about plagiarism

Plagiarism is an action of copy others ideas without any acknowledgement of source. According to the Longman Dictionary of contemporary English(1995), define that use others ideas and words as your own ideas when you write the essay is plagiarism. The oxford(1992) presented the plagiarism as---"a kidnapper or literary thief ". However, the book Academic Writing(1989) conclude that the national students have different academic background, so they will not realize they have copy the ideas from books, articles and newspapers should be show the sourced. So they are always intentionally to plagiarism.