reference center reference centres reference centre reference checks reference clock reference code reference collection reference conditions reference configuration reference criteria reference currency reference database reference data reference date reference design reference documentation reference documents reference document reference electrode reference electrolyte reference exchange rate reference field reference file reference flow reference for a preliminary ruling concerns reference for a preliminary ruling reference for the development reference frameworks reference framework reference frame reference frequency reference fuels reference gas reference groups reference group reference guide reference has been made reference has reference headphones reference images reference image reference implementation reference in the field reference in the report reference in the sector reference income reference index reference information reference input reference intake reference interest rate reference is also made reference is made reference laboratories reference laboratory reference letters reference letter reference levels reference level reference library reference line reference list reference literature reference load reference management reference manager reference manual reference market reference mark reference mass reference materials reference material reference may reference measurements reference medicinal product reference medicine reference member state reference methods reference method reference model reference monitor reference month reference must be made reference must reference networks reference numbers reference number reference offer reference page reference period for calculating reference periods reference period reference person reference photo reference picture reference pitch reference place reference plane reference platform reference points reference point reference population reference position reference power reference presentation reference pressure reference price system reference prices reference price reference product reference projects reference purposes reference quantities reference quantity reference range reference rates reference rate reference resources reference room reference samples reference sample reference scenario reference section reference selection reference sensor reference sequence reference series reference service reference should be made reference should reference signal reference site reference software reference solution reference sources reference source reference standards reference standard reference state reference stations reference station reference substances reference surface reference systems reference system reference table reference temperature reference test reference texts reference text reference time reference to a product reference to annex reference to any products reference to article reference to chapter reference to directive reference to god reference to human rights reference to information reference to international standards reference to it reference to national law reference to nationality reference to one reference to paragraph reference to regulation reference to religion reference to research reference to services reference to the agreement reference to the application reference to the charter reference to the committee reference to the concept reference to the date reference to the definition reference to the existence reference to the fact reference to the importance reference to the law reference to the list reference to the name reference to the need reference to the objectives reference to the place reference to the possibility reference to the principle reference to the problem reference to the right reference to the role reference to the rules reference to the situation reference to the source reference to the term reference to the treaty reference to the type reference to the use reference tone reference tool