In any case, the author of the paper must indicate the author and source of the quoted text. At present, the common practice in American academic circles is to indicate the author and source of the quotation in brackets after the quotation.
Extended data:
If the quotation is less than three lines, the quotation can be organically integrated into the paper. For example:
The separation of Arnold's personal desire and his legacy led to "a familiar picture of Victorian people living alone in a strange universe" (Roper 9).
Here, the Roper in brackets is the last name of the author of the citation (full name is not required); Arabic numerals are the page numbers of quotations (don't write P.9);
There should be a space between the author's surname and the page number, but punctuation is not needed; The period should be placed after the second parenthesis.
If you need to insert notes in the quotation to explain some words, use square brackets (not parentheses). For example:
Dr. Beaman pointed out that "he (Charles Darwin) is an important factor in the debate between evolution and biblical creationism".
It is worth noting that in this case, the surname of the author of the quotation has already appeared in the leading sentence, so it is only necessary to indicate the page number of the quotation in brackets.