In Name and Year (N-Y) System, each citation in text is designated by the last name(s) of the author(s) followed by the year of publication of the document. The name and the date are enclosed within parentheses. The citations are arranged in the "References" section by the alphabetic order of the last name of first author of the document that you are citing.
Example: For instance, siblings or maternal half siblings born in different breeding seasons might learn to recognize each other as a result of association with their common parent or parents (Sherman 1980).
To accommodate the in-text citations of multiple works published by the same author, authors with identical last names, multiple authors, corporations and organizations as authors, works with ”unidentifiable authorship” and works with multiple dates, the N-Y format needs to be modified. Following are the examples.
Documents Published by the Same Author in Different Years
Documents published by the same author in different years should be cited in chronologic order.
Same author in the same year
To refer to more than one work by the same author published in the same year, use alphabetic designators (e.g. a,b,c) with the year.
Authors with Identical last names
If you cite the works of two authors who have identical last names and their works published in the same year, include the authors’ last name and initials both in-text references with the years and separate them by a semicolon and a space.
Citation of a work with authors
If a cited work has two authors, mention both last names, separated by "and".
If both authors have the same last name, use their initials in the in-text citation.
Three or more author citations
Documents with three or more authors are cited by the last name of first author followed by "and others" or "et al" and the publication year. Do not use a comma before et al.; always use a period after al.
Corporations or Organizations as author
Corporate or organizational names cited as authors should be given in an abbreviated form or acronym. Use the initial letter of each part of the name or a readily recognizable abbreviation to create a shortened form for the in-text reference. This shortened form, within square brackets, becomes the initial element in the reference.
If the author is not known or cannot be identified, do not use "anonymous". Cite the document in the text using the first or first few words of the title, followed by an ellipsis.
In-text reference of multiple works by the same author
When you cite multiple works of an author whose name is a part of a sentence, place the year in parentheses in chronological order, if you follow N-Y system.
Multiple citations at 1 point
When two or more documents are cited together in parentheses, they should be cited in a chronologic order from earliest to latest. Those published in the same year should be sequenced alphabetically by author’s name.
Works with no dates
Sometimes with older publications or manuscripts as well as some web publications, it is not possible to find any dates associated with the documents. For in-text references, these publications with no dates should be mentioned with the words “date unknown” within square brackets.