1. Berk, J., & DeMarzo, P. (2020). Corporate Finance (5th ed.). Pearson. In Chapter 23, Section 23.2, the text explains preferred stock features, stating, "If the dividend is non-cumulative, any missed dividend payments do not accumulate... the firm can pay current dividends to common stockholders without first paying the missed preferred dividends."
2. Ross, S. A., Westerfield, R. W., & Jaffe, J. (2019). Corporate Finance (12th ed.). McGraw-Hill Education. Chapter 14, Section 14.2, describes preferred stock and notes that for non-cumulative issues, "if preferred dividends are not paid in a particular year, they are not carried forward."
3. Fooladi, I. J., & Roberts, G. S. (1986). An Analysis of the Characteristics of Preferred Stock. The Journal of Financial Research, 9(3), 249–256. On page 250, the article distinguishes between cumulative and non-cumulative dividend provisions, clarifying that with non-cumulative preferreds, "the dividend is lost forever if not paid." https://doi.org/10.1111/j.1475-6803.1986.tb00443.x