Dreighton Engineering Group receives royalties on a technical manual written by two of its engineers and sold to William B. Irving Publishing, Inc. Royalties are 10% of net sales, receivable on October 1 for sales in January through June and on April 1 for sales in July through December of the prior year. Sales of the manual began in July 2020, and Dreighton accrued royalty revenue of $31,000 at December 31, 2020, as follows:

Receivable—royalty revenue 35,000 Royalty revenue 35,000 Dreighton received royalties of $41,000 on April 1, 2021, and $45,000 on October 1, 2021. Irving indicated to Dreighton on December 31 that book sales subject to royalties for the second half of 2021 are expected to be $550,000. Prepare any necessary journal entry related to royalty revenue and adjustment if any made to retained earnings or the 2020 financial statements.