https://www.bibliotecapleyades.net/luna/luna_moonanomalies15.htm

Contrary to popular belief, reports of artificial structures on the moon are both common and persistent.  

Among the first were from George Leonard's 1976 book, Somebody Else is on The Moon, and Fred Steckling's 1981 book, We Discovered Alien Bases on The Moon. 

There are many more, and from many credible sources, which we will get to later in the article.