Sarah, CPA, is engaged to audit the financial statements of Advanced Wholesaling for the year ended December 31, 2020. Saran cotained and oscumented an understanding of the internal controls relating to the accounts receivable and assessed control risk at the min mum level she requested and oceaned from Advanced, an aged accounts receivable schedule listing the invoices by date and the total amount owed by each custonter as of December 31, 2020 Sarah then sent positive confirmacod requests to a sample of customers. Required: What additional substantive audit procedures should Sarah consider applying in auditing the accounts receivable?