Written reference requirement mandates electronic submissions identifying suspected undervaluation and evidence, enabling administrative examination and screening. Rule 6 requires the Board to rely on an electronically submitted written reference from any person (or specified officials) alleging that imported goods are undervalued; such references must include identity and contact details (except for government representatives), a complete goods description with HS code and origin, the alleged method of undervaluation, supporting documentary evidence and analysis, an approximate quantification of undervaluation, other reliable information sources, and suggested additional checks, and must be forwarded electronically by the Board to the Screening Committee for examination.