• Determinants and pricing models of audit fees: multi-dimensional size, recent auditor change, and client-auditor fit drive fees; empirical frameworks explain a large share of fee variation, with assets and sales used as size measures and switching effects considered [14], [15], [17], [5], [1].

• Audit quality as credibility: perceived auditor quality, earnings response, and report interpretation shape investor reactions and valuation; report form and going-concern context modulate credibility signals across users [8], [11], [10], [13].

• Auditor switching and signaling: switching as a strategic response with mixed effects on opinions, supported by informational signaling and replacement behavior [2], [12], [3].

• Governance and regulatory environment impact on audits: audit committees, liability/regulatory pressures, and market structure influence independence, pricing, and user trust [18], [9], [4].

• Cross-country/international context and practice differences: Singaporean audit-fee determinants and cross-market valuation patterns illustrate contextual variation in audit practice [20], [16], plus related governance implications [11].