Cost of Debt for Private Firms Revisited: Voluntary Audits as a Reflection of Risk
R. Ichev, J. Koren, U. Kosi, K. Sitar Sustar, A. Valentincic, Cost of Debt for Private Firms Revisited: Voluntary Audits as a Reflection of Risk, 2021.

Does Financial Statement Audit Reduce the Cost of Debt of Private Firms?
U. Kosi, J. Koren, A. Valentincic, in: 2013.