AI search engines cite sources in three steps: they retrieve candidate pages they can reach, select the ones they trust most, and attribute a specific claim to them. Selection favours specificity and corroboration, so a model prefers a precise claim it can verify across several sources over a vague statement it cannot pin down. A page is only citable if a crawler can read it, which rules out gated PDFs and script-only content. The most quotable format is a clear question as a heading followed by a direct, two-sentence answer.