Searching for X-rated movies

Obviously imdb.com is the go-to source for ratings of non-X-rated movies, but, I have not found one yet for X-rated movies.  Typically when I search for one on imdb.com, it returns no results, yet, many times I find the movie via a Google link to imdb.com.  For example, "Femmes De Sade" (1976) is not found via the search bar, but, exists on imdb.com as "tt0074523".  Is there a setting on imdb.com that I am missing that I need to set to be able to search for and find X-rated movies?