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 $40,600 at December 31, 2020, as follows:

Receivableroyalty revenue	40,600
Royalty revenue		40,600

Dreighton received royalties of $48,000 on April 1, 2021, and $52,000 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 $620,000. Required: 1. & 2. Prepare any necessary journal entry related to royalty revenue for 2021 and record adjustment, if any, made to retained earnings in the 2020 financial statements. (If no entry is required for a transaction/event, select "No journal entry required" in the first account field.)