Skip to main content

APA Citation Style (6th edition)

Integrating sources --Signal Phrases

A signal phrase often names the author of the source, gives the publication date in parentheses, and can provide some context in your work.

  • Try one of these signal phrases to help create a smooth transition within your text:
    • As Flynn (2010) claimed  “…” (p. 98).
    • Pappas and Murray (2009) reported “…” (p. 67).
    • Research suggested “…" (Smith, 1999, p. 19).
  • Signal word examples:  admitted, asserted, demonstrated, compared, reasoned, argued, showed that, supported
  • APA requires using verbs in the past tense or present perfect tense (argued or has argued)

Adapted from: Hacker, D. & Sommers, N. (2012). A Canadian writer's reference (5th ed.).

Sample paragraphs

Here's a sample paragraph with in-text citations (bold is for emphasis only; do not do this in your paper).

            A carbon tax is "usually defined as a tax based on greenhouse gas emissions (GHG) generated from burning fuels. It puts a price on each tonne of GHG emitted, sending a price signal that will, over time, elicit a powerful market response across the entire economy, resulting in reduced emissions" (Province of British Columbia, Ministry of Finance, n.d., para. 1). How is the price set for each tonne of gas emission? And what are the factors than influence the pricing?

           According to Patel (2011) the theory behind carbon pricing is the assumption that the market will price it fairly. This theory ignores the fact that special interest groups, such as oil companies and known industrial polluters, are vocal in their opposition to governments asking for limits to the impact of carbon taxes. Conflicting scientific opinion and uncertainties about climate change and its possible effect are huge, making the economic argument for strict GHG reductions far from clear (Pindyck, 2013, p. 44).


Patel, R. (2011). The value of nothing: How to reshape market society and redefine democracy. London: Portobello.

Pindyck, R. S. (2013). Pricing carbon when we don't know the right price. Regulation, 36(2), 43-46. Retrieved from

Province of British Columbia, Ministry of Finance. (n.d.). What is a carbon tax? Retrieved from