Columbia subject headings:
Twain, Mark, 1835-1910.
Harvard subject headings:
Authors, American--20th century--Biography--Juvenile literature
Quick, Dorothy, 1900-1962--Friends and associates--Juvenile literature.
Twain, Mark, 1835-1910
Twain, Mark, 1835-1910--Friends and associates--Juvenile literature.
Princeton subject headings:
Twain, Mark, 1835-1910.