In her 1998 book Blues Legacies and Black Feminism, Angela Y. Davis bases her analysis in part on recordings of songs sung in the 1920s by Gertrude “Ma” Rainey and Bessie Smith. Davis focuses on how Rainey and Smith improvised the lyrics—replacing the original lines with mischievous jokes and wordplay. Davis’s work was particularly labor intensive because in order to transcribe, or write down, the lyrics as Rainey and Smith sang them, Davis had to listen repeatedly to the vinyl recordings, which weren’t very clear.