Explanation

Subsidiary books are journals where specific types of transactions are first recorded. Sales day book, purchase day book, and return inward day book are all subsidiary books that organize different transaction types.

A credit note is a document given to customers, not a book for recording transactions. It proves a refund or price reduction was given. The transaction goes in return inwards day book.

Key point: Subsidiary books record transactions. Credit notes are source documents that provide evidence of transactions.