Charlotte, to Anne or Emily' is a reference to the Bronte sisters, Charlotte, Anne, and Emily. Charlotte Bronte was an English novelist and poet who wrote the novel Jane Eyre. Her sisters, Anne and Emily, were also authors, writing novels such as The Tenant of Wildfell Hall and Wuthering Heights, respectively. The crossword solution 'SIS' is an abbreviation for sister, referring to the Bronte sisters.