it is ALWAYS important to cites ALL of your sourses to avoid plagiarism. I normally at the end of my paper make a new paragraph and title it "Works Cited". type citation machine into google for more help writing a fromal citation. Remember most junior and high schools only allow certan citation styles but your best bet is either APA or MLA. hope this helped.
Teachers should write a formal letter to welcome the parent or guardian
Not for sure what your paragraph is about, but here a few words for you :)
Sui Generis: being the only example of its kind, unique
Profligate: using money, resources, etc., in a way that wastes them
Obduracy: refusing to change in any way
Obstreperous: very noisy or difficult to control
