How did Crosby, Stills, Nash & Young get their name?

Crosby, Stills & Nash (CSN) was a folk rock supergroup made up of American singer-songwriters David Crosby and Stephen Stills and English singer-songwriter Graham Nash. They were known as Crosby, Stills, Nash & Young (CSNY) when joined by Canadian singer-songwriter Neil Young, who was an occasional fourth member.