Consider the following paragraph in a research essay:

        Serialization was the dominant form of publication in the nineteenth century.  Economic factors encouraged this Victorian reading in parts, of course, as industrialization provided steam power, made material cheaper, and increased the number of literate citizens.  Paying by installments also expanded the book trade.  But just as important, "serialization was aligned with fundamental middle-class values:  a belief in historical progress; acceptance of biological evolution; and commitment to the ideal of marriage and family extending over time" (Lund 14).

At first, it might seem that Lund contributed only what is in direct quotes here, "serialization . . . time" (which I have put in pink; I have put the acknowledgment in blue).  However, there are two possible situations represented here.

Suppose first that some of Lund's points had been summarized or paraphrased in the two sentences preceding the one which includes a direct quotation.  In this case, the author has plagiarized, and Lund might well sue, arguing that the author had taken his ideas and used them without acknowledgment.

The correct format for passage 1 is as follows:

        Serialization was the dominant form of publication in the nineteenth century. According to Lund, economic factors encouraged this Victorian reading in parts, of course, as industrialization provide steam power, made material cheaper, and increased the number of literate citizens.  Paying by installments also expanded the book trade.  But just as important, "serialization was aligned with fundamental middle-class values:  a belief in historical progress; acceptance of biological evolution; and commitment to the ideal of marriage and family extending over time" (14).

One might also document the paragraph as follows:

        Serialization was the dominant form of publication in the nineteenth century. According to Lund, economic factors encouraged this Victorian reading in parts, of course, as industrialization provide steam power, made material cheaper, and increased the number of literate citizens. Lund also notes that paying by installments also expanded the book trade.  But just as important, Lund concludes, "serialization was aligned with fundamental middle-class values:  a belief in historical progress; acceptance of biological evolution; and commitment to the ideal of marriage and family extending over time" (14).

    Now suppose a second situation in which Lund had not been the source for the two sentences that preceded the one in which he is quoted, and the paragraph was documented as before (I present it again here):

        Serialization was the dominant form of publication in the nineteenth century.  Economic factors encouraged this Victorian reading in parts, of course, as industrialization provided steam power, made material cheaper, and increased the number of literate citizens.  Paying by installments also expanded the book trade.  But just as important, "serialization was aligned with fundamental middle-class values:  a belief in historical progress; acceptance of biological evolution; and commitment to the ideal of marriage and family extending over time" (Lund 14).

The author has done nothing to establish where Lund's ideas begin here because material can be presented by paraphrase or summary (that is, without quotation marks) as well as by direct quotation. The author has simply stuck "(Lund 14)" at the end of a reference, the beginning of which cannot be determined.  Suppose also that Lund didn't believe those two statements preceding the one in which he is quoted to be true.  He might sue the author for suggesting Lund had made those points because nothing in the way this paragraph is constructed precludes that possibility.    The correct form for this situation is as follows:

     Serialization was the dominant form of publication in the nineteenth century.  Economic factors encouraged this Victorian reading in parts, of course, as industrialization provide steam power, made material cheaper, and increased the number of literate citizens.  Paying by installments also expanded the book trade.  But just as important, argues Lund, "serialization was aligned with fundamental middle-class values:  a belief in historical progress; acceptance of biological evolution; and commitment to the ideal of marriage and family extending over time" (14).

That is, in order to avoid intentional and unintentional plagiarism, every reference--factual information, direct quotations, paraphrase, or summary--must begin with an acknowledgment, such as "The author has written . . . , " "According to the writer . . . ," "Author states that . . . ."  (When you don't have an author's name, of course, you have to use a title in your introduction to the reference--"The New York Times says . . . " or "Report of X Commission indicates that . . . " and sometimes a portion of the title in the parentheses before the page number at the end.)

For MLA format in the Works Cited,  see this site http://www.dianahacker.com/resdoc/humanities/english.html  at Writing at Longwood.