Md. Code, Election Law § 13–403

(a) (1) Subject to paragraph (2) of this subsection, each campaign finance entity, each person required to register under § 13–306(b) of this title, and each person required to register under § 13–307(b) of this title that is responsible for, publisher of, and distributor of, an item of campaign material shall keep a sample copy of the item for at least 1 year after the general election next following the date when the item was published or distributed.

(2) For each item of campaign material disseminated through the Internet, the sample copy shall be:

(i) a paper facsimile; or

(ii) a copy on an electronic medium that can be produced as a paper facsimile on request.

(b) Subsection (a) of this section does not apply to a billboard or a sign.