CREATE TABLE table_20174050_23 (reader VARCHAR2, format VARCHAR2, author VARCHAR2)

who is the reader on the download/cd format of the title written by author lidster, joseph joseph lidster?
SELECT reader FROM table_20174050_23 WHERE format = "Download/CD" AND author = "Lidster, Joseph Joseph Lidster"
SELECT "reader" FROM "table_20174050_23" WHERE "Download/CD" = "format" AND "Lidster, Joseph Joseph Lidster" = "author"