A tonicized chord is a chord to which a secondary dominant progresses. For example, if chord ii comes after V/ii it has been tonicized. Only major and minor chords may be tonicized. Though perceptions vary  as a general rule if a chord is treated as the tonic for longer than a phrase then the treatment is considered a modulation.
- Benward & Saker (2003). Music: In Theory and Practice, Vol. I, p.270. ISBN 978-0-07-294262-0.
- Bartlette, Christopher, and Steven G. Laitz (2010). Graduate Review of Tonal Theory. New York: Oxford University Press, pg 137. ISBN 978-0-19-537698-2
- Kostka, Stefan and Dorothy Payne (2003). Tonal Harmony, p.289. "The line between modulation and tonicization...is not clearly defined in tonal music, nor is it meant to be." ISBN 0-07-285260-7.
- Gauldin, Robert (1997). Harmonic Practice in Tonal Music New York: W.W. Norton & Company, pg 366. ISBN 0-393-97666-1