Format: 

Lastname, Firstname. "Title of Article." Title of Newsletter, Publisher or Organization, Day Month Year, Page(s). Database Name or Title of Non-Publisher Website, URL. Accessed Day Month Year.

Lastname, Firstname. "Title of Article." Title of Newsletter, Publisher or Organization, Day Month Year, Page(s), URL or DOI (when accessed from the publisher's website). Accessed Day Month Year.

Lastname, Firstname. "Title of Article." Title of Newsletter, Publisher or Organization, Day Month Year, Page(s).

Examples: 

Ritieni, Assunta. "Increasing Awareness of Chemicals in Personal Care Products." Your Health and the Environment, University of Rochester Environmental Health Science Center, Summer 2014, p. 4, urmc.rochester.edu/MediaLibraries/URMCMedia/environmental-health-sciences-center/COEC/documents/Summer2014EHSC.pdf. Accessed 12 Dec. 2017.

In-text: (Rochester Regional Health)

"Brighton Highway Winter Policies." Town of Brighton Newsletter and Recreation and Parks Brochure, Town of Brighton, 6 Aug. 2017, p. 3. Issuu, issuu.com/gvpublications/docs/brighton_town_nws_17-2301_web. Accessed 12 Dec. 2017.

In-text: ("Brighton Highway")

Notes: 

If you are accessing a newsletter article directly from the organization's website, provide the URL immediately after the page numbers for the article preceded by a comma. If the article is published only online without page numbers, use the URL in place of the page numbers, but omit the http:// or https:// (MLA 110). Since newsletters are often not widely distributed sources and the link can change, include an access date (see first example) (MLA 53). If you are accessing the newsletter from a third party website (e.g. Issuu), include the title of the website, URL, and date of access at the end of the citation (see second example). For instances where the article is not published on consecutive pages, include only the first page number immediately followed by a plus sign (e.g. 24+) (MLA 110). If you do not know the individual author of an article, you may cite the corporate author; if the corporate author and the publisher are the same, omit the author (see second example) (MLA 24). If the newsletter is untitled, provide a brief description (e.g. Newsletter for RIT Libraries) in place of the title, but do not italicize it (https://style.mla.org/citing-untitled-newsletter).

Source:
MLA - p. 30