Notes on verification

Confirmed by multiple independent, authoritative sources including official Willy Brandt biography project, SPD's own website, and Wikipedia, all consistent on name, date, and place of birth. [cascade flags: wikipedia_dropped_other_sources_exist | tier=bronze indep_score=0.525 clusters=4 claim_tier=notable | framework convergence=partial (upstreams: Willy Brandt official biography project (willy-brandt-biography.com), SPD (Social Democratic Party of Germany)) — publishers independent, evidence may not be | kind=empirical eligibility=high]