Most of the articles or  papers need to have  a documentation support. 
The context of disciplines can be diverse  for example in engineering field if you need to develop an essay is necessary to investigate in   the scientific community who is writing about the  topic (state of art). 
The APA standards  does suggest to use the forms of documentation as:
In- text citation and work-cited list.
Example of in- text citation: The saw welding process is usually used in USA ( espinoza, 2018). 
Example of work-cited list.
Bibliography.
1. James and dawson, inspection of pressure vessel to ASME Section VIII Div 1, presented at taking Pressure Vessel from Cradle to grave, Singapura, 2011. 
 
        
                    
             
        
        
        
Answer:
Look in the back cover or in the index.
 
        
             
        
        
        
The author is J. B. Priestley
 
        
                    
             
        
        
        
No one wrote that, you are able to write your own product reviews though.
 
        
             
        
        
        
Answer: Students like mathematics teachers because <u>the teachers</u> are practical.
Explanation:
      This sentence is saying that students like math teachers. This means that the "they" <em>is </em>the math teachers. 
       We can rewrite the sentence to make the pronoun clearer by replacing it as so;
Students like mathematics teachers because the teachers are practical.
       Please note there are <em>many</em> ways to rewrite the sentence, this is just one of them.
Pronouns are words replacing nouns in a sentence. 
Examples include he, she, they, him, it, etc. 
<em>Read more about your question here:</em>
<em>brainly.com/question/1979855</em>