| APA | Smart Define. (2013). past progressive tense thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/past_progressive_tense/thesaurus/synonyms |
| Chicago | Smart Define. 2013. "past progressive tense thesaurus" https://smartdefine.org/past_progressive_tense/thesaurus/synonyms (accessed September 22, 2026). |
| Harvard | Smart Define 2013, past progressive tense thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/past_progressive_tense/thesaurus/synonyms>. |
| MLA | Smart Define. "past progressive tense thesaurus" 18 May 2013. Web. 22 September 2026. <https://smartdefine.org/past_progressive_tense/thesaurus/synonyms> |