Ax 2012 lookup reference sample

public Common lookupReference(FormReferenceControl _formReferenceControl)
{

HcmWorker HcmWorker;
Query query = new Query();
QueryBuildDataSource queryBuildDataSource;
QueryBuildRange queryBuildRange;

SysReferenceTableLookup sysTableLookup = SysReferenceTableLookup::newParameters(tableNum(HcmWorker), _formReferenceControl, true);
;
sysTableLookup.addLookupField(fieldNum(HcmWorker, PersonnelNumber));
sysTableLookup.addLookupField(fieldNum(HcmWorker, Person));

queryBuildDataSource = query.addDataSource(tableNum(HcmWorker));

return sysTableLookup.performFormLookup();

}