When writing an english artical, we always need to take care of the citation to avoid the accusation of plagiarism. For a typical artical in Science, we need to apply APA citation style.
The APA citation style requires both the in-text citations and a appending reference list.

The following instructions comes from cornell uni's website
http://www.library.cornell.edu/node/147

Reference Citations in Text

In APA style, in-text citations are placed within sentences and paragraphs so that it is clear what information is being quoted or paraphrased and whose information is being cited.

Examples:

Works by a single author

The last name of the author and the year of publication are inserted in the text at the appropriate point.

from theory on bounded rationality (Simon, 1945)

If the name of the author or the date appear as part of the narrative, cite only missing information in parentheses.

Simon (1945) posited that

 

Works by multiple authors

When a work has two authors, always cite both names every time the reference occurs in the text. In parenthetical material join the names with an ampersand (&).

as has been shown (Leiter & Maslach, 1998)

In the narrative text, join the names with the word "and."

as Leiter and Maslach (1998) demonstrated

When a work has three, four, or five authors, cite all authors the first time the reference occurs.

Kahneman, Knetsch, and Thaler (1991) found

In all subsequent citations per paragraph, include only the surname of the first author followed by "et al." (Latin for "and others") and the year of publication.

Kahneman et al. (1991) found

 

Works by associations, corporations, government agencies, etc.

The names of groups that serve as authors (corporate authors) are usually written out each time they appear in a text reference.

(National Institute of Mental Health [NIMH], 2007)

When appropriate, the names of some corporate authors are spelled out in the first reference and abbreviated in all subsequent citations. The general rule for abbreviating in this manner is to supply enough information in the text citation for a reader to locate its source in the Reference List without difficulty.

(NIMH, 2007)

 

Works with no author

When a work has no author, use the first two or three words of the work's title (omitting any initial articles) as your text reference, capitalizing each word. Place the title in quotation marks if it refers to an article, chapter of a book, or Web page. Italicize the title if it refers to a book, periodical, brochure, or report.

on climate change ("Climate and Weather," 1997)

Guide to Agricultural Meteorological Practices (1981)

 

Anonymous authors should be listed as such followed by a comma and the date.

on climate change (Anonymous, 2008)

 

Specific parts of a source

To cite a specific part of a source (always necessary for quotations), include the page, chapter, etc. (with appropriate abbreviations) in the in-text citation.

(Stigter & Das, 1981, p. 96)

If page numbers are not included in electronic sources (such as Web-based journals), provide the paragraph number preceded by the abbreviation "para." or the heading and following paragraph.

(Mönnich & Spiering, 2008, para. 9)

 

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Reference List

For a much much much easier work, use tools like Endnotes or Harvard reference generator

References cited in the text of a research paper must appear in a Reference List or bibliography. This list provides the information necessary to identify and retrieve each source.

• Order: Entries should be arranged in alphabetical order by authors' last names. Sources without authors are arranged alphabetically by title within the same list.
• Authors: Write out the last name and initials for all authors of a particular work. Use an ampersand (&) instead of the word "and" when listing multiple authors of a single work. e.g. Smith, J. D., & Jones, M.
• Titles: Capitalize only the first word of a title or subtitle, and any proper names that are part of a title.
• Pagination: Use the abbreviation p. or pp. to designate page numbers of articles from periodicals that do not use volume numbers, especially newspapers. These abbreviations are also used to designate pages in encyclopedia articles and chapters from edited books.
• Indentation*: The first line of the entry is flush with the left margin, and all subsequent lines are indented (5 to 7 spaces) to form a "hanging indent".
• Underlining vs. Italics*: It is appropriate to use italics instead of underlining for titles of books and journals.

Two additional pieces of information should be included for works accessed online.

• Internet Address**: A stable Internet address should be included and should direct the reader as close as possible to the actual work. If the work has a digital object identifier (DOI), use this. If there is no DOI or similar handle, use a stable URL. If the URL is not stable, as is often the case with online newspapers and some subscription-based databases, use the home page of the site you retrieved the work from.
• Date: If the work is a finalized version published and dated, as in the case of a journal article, the date within the main body of the citation is enough. However, if the work is not dated and/or is subject to change, as in the case of an online encyclopedia article, include the date that you retrieved the information.

* The APA has special formatting standards for the use of indentation and italics in manuscripts or papers that will be typeset or submitted for official publication. For more detailed information on these publication standards, refer to the Publication Manual of the American Psychological Association, or consult with your instructors or editors to determine their style preferences.

** See the APA Style Guide to Electronic References for information on how to format URLs that take up more than one line.

Examples:

Articles in journals, magazines, and newspapers

References to periodical articles must include the following elements: author(s), date of publication, article title, journal title, volume number, issue number (if applicable), and page numbers.

Journal article, one author, accessed online

 

Journal article, two authors, accessed online

 

Journal article, more than two authors, accessed online

 

Article from an Internet-only journal

 

Journal article from a subscription database (no DOI)

 

Magazine article, in print

Kluger, J. (2008, January 28). Why we love. Time, 171(4), 54-60.

 

Newspaper article, no author, in print

 

Newspaper article, multiple authors, discontinuous pages, in print

 

Books

References to an entire book must include the following elements: author(s) or editor(s), date of publication, title, place of publication, and the name of the publisher.

No Author or editor, in print

 

One author, in print

 

Two authors, in print

 

Corporate author, author as publisher, accessed online

 

Edited book

 

Dissertations

References for dissertations should include the following elements: author, date of publication, title, and institution (if you accessed the manuscript copy from the university collections). If there is a UMI number or a database accession number, include it at the end of the citation.

 

Dissertation, accessed online

 

Essays or chapters in edited books

References to an essay or chapter in an edited book must include the following elements: essay or chapter authors, date of publication, essay or chapter title, book editor(s), book title, essay or chapter page numbers, place of publication, and the name of the publisher.

One author

 

Two editors

 

Encyclopedias or dictionaries and entries in an encyclopedia

References for encyclopedias must include the following elements: author(s) or editor(s), date of publication, title, place of publication, and the name of the publisher. For sources accessed online, include the retrieval date as the entry may be edited over time.

 

Encyclopedia set or dictionary

 

Article from an online encyclopedia

 

Encyclopedia article

 

Research reports and papers

References to a report must include the following elements: author(s), date of publication, title, place of publication, and name of publisher. If the issuing organization assigned a number (e.g., report number, contract number, or monograph number) to the report, give that number in parentheses immediately after the title. If it was accessed online, include the URL.

 

Government report, accessed online

 

Government reports, GPO publisher, accessed online

 

Technical and/or research reports, accessed online

 

Document available on university program or department site

 

Audio-visual media

References to audio-visual media must include the following elements: name and function of the primary contributors (e.g., producer, director), date, title, the medium in brackets, location or place of production, and name of the distributor. If the medium is indicated as part of the retrieval ID, brackets are not needed.

Videocassette/DVD

 

Audio recording

 

Motion picture

 

Television broadcast

 

Television show from a series

 

Music recording

 

Undated Web site content, blogs, and data

For content that does not easily fit into categories such as journal papers, books, and reports, keep in mind the goal of a citation is to give the reader a clear path to the source material. For electronic and online materials, include stable URL or database name. Include the author, title, and date published when available. For undated materials, include the date the resource was accessed.

 

Blog entry

 

Professional Web site

 

Data set from a database

 

Entire Web site
When citing an entire Web site (and not a specific document on that site), no Reference List entry is required if the address for the site is cited in the text of your paper.

 

Comparison of citation elements: notes vs. bibligraphy

In general terms, notes and bibliographic citations contain many of the same elements. While a footnote/endnote gives the specific page on which the quote or information appears, a bibliographic entry contains the inclusive page numbers of the work cited. The second footnote/endnote about the same source contains enough information to identify the work. In contrast, a bibliography contains the information for each source only once.

Suggested content of footnotes

APA format suggests using footnotes for two types of information: content comments and copyright permission.

A content comment footnote discusses a single idea that supplements or amplifies your point within the text.

Example of a content footnote:

²Until recently the teaching of cross-disciplinary meta-literacy skills has not been discussed in the literature of school librarianship.

A copyright permission footnote acknowledges the source of a quotation or the source of a reprinted table or figure.

Example of a copyright permission footnote for a reprinted chart from periodical:

²The chart is from "A Seven-Power Lens on 21st-Century Literacy" by D. Abilock, 2003, Multimedia Schools, 10, p. 30. Copyright 2003 by Debbie Abilock. Reprinted with permission.