Where Two People Are Writing the Same Book, Each Believes He Gets All the Worries and Only Half the Royalties

Agatha Christie? James Beasley Simpson? Joe Bushkin? Leonard Lyons? Apocryphal? Dear Quote Investigator: Successful collaboration is difficult to achieve for many creators. The outstanding mystery writer Agatha Christie once referred to the difficulty of splitting royalties while explaining why she did not have coauthors. Would you please help me to find her remark? Quote Investigator: …