When we cite sources, we want to make them fit into our writing as smoothly as possible. When integrating sources into our papers, it's important to use signal phrases that help us:

Establish the authority of the people we're citing
Introduce summaries and paraphrases
Put direct quotes in context
Integrate statistics and other facts.

Below are some examples of signal phrases and in-text citations that we might use. Note that these examples have the in-text citations bolded to show us what they look like as part of a sentence but in our own papers, we would not bold our in-text citations.

When introducing an author and including a direct quote:

In his book An Inconvenient Truth, Al Gore (2006) warns, "global warming, along with the cutting and burning of forests and other critical habitats, is causing the loss of living species at a level comparable to the extinction event that wiped out the dinosaurs 65 million years ago. That event was believed to have been caused by a giant asteroid. This time it is not an asteroid colliding with the Earth and wreaking havoc; it is us" (p. 10).

When including a direct quote (without introduction of the author):

Scientific research on the impact of global warming abounds and climate variability has recently received much-needed attention, providing opportunities to "probe causes of the climate variability simulated by coupled climate models that can reproduce reliable long-term climate variations" (Liu et al., 2012, p. 1064).

When summarizing or paraphrasing the work of the author:

There are four types of greenhouse gases: carbon dioxide, methane, nitrous oxide, and fluorinated gases (U.S. Environmental Protection Agency, 2013).

Example

Below is an example of what the corresponding bibliographic citations would look like in the References page at the end of the paper or project:

References

Gore, A. (2006). An Inconvenient Truth: The planetary emergency of global warming and what we can do about it. Emmaus, PA: Rodale Press.

Liu, J., Wang, B., Yim, S.Y., Lee, J.Y., Jhun, J.G., & Ha, K.J. (2012). What drives the global summer monsoon over the past millennium? Climate Dynamics, 39(5), 1063–1072. doi:10.1007/s00382-012-1360-x

U.S. Environmental Protection Agency. (2013, September 9). Overview of Greenhouse Gases. Greenhouse Gas Emissions. Overviews & Factsheets. Retrieved November 27, 2013, from http://www.epa.gov/climatechange/ghgemissions/gases.html

More Than One Author?

Refer to the OWL APA section on In-Text Citations: Author/Authors for how to create in-text citations when a source has multiple authors.