How does Higgins know where all the bystanders are from?
It is in his notebook.
He can tell by their dress and mannerisms.
He listened to their earlier conversation where they discussed it.
He can tell by their language use.

there is no passage.

harlem's  cotton club boasted the talents of duke ellington. singers such as bessie smith and billie holiday popularized blues and jazz vocals. jelly roll morton and louis armstrong drew huge audiences as white americans as well as african americans caught jazz fever.

123 are right hope ths