CQ Researcher is an unusual source because it's sort of both a database and a journal at the same time. So the best citation format you should use is for a journal article, and the name of the journal is CQ Researcher.
Here is an example of a citation from CQ Researcher done in MLA, 8th edition style:
Hosansky, David. "Traffic Congestion." CQ Researcher, 26 Jan. 2018, pp. 73-96,
Nelson Poynter, former journalist and owner of the St. Petersburg Times, and his wife Henrietta, founded Congressional Quarterly in 1945. Poynter's vision for Congressional Quarterly was to make transparent the happenings within the government and Washington, DC. Poynter established the Modern Media Institute, now known as the Poynter Institute, with the mission of promoting democracy through education to journalists and other media leaders. After Poynter's death in 1978, the Institute received controlling stock of the St. Petersburg Times and ownership of CQ.
In May 2008, CQ Press was purchased from Congressional Quarterly by SAGE Publications in its entirety. SAGE is an international publisher of journals, books, and electronic media for academic, educational, and professional markets. A privately owned corporation, SAGE has offices in Los Angeles, London, New Delhi, and Singapore, in addition to the CQ Press office in Washington, DC.