As starters, I suggest: NUREG/CR-4884, Interpretation of Bioassay Measurements ICRP 54, Individual Monitoring for Intakes of Radionuclides by Workers: Design and Interpretation (Note that this is not entirely conformant to the first document, in a number of ways. They're complementary) HPS N13.30-1996, An American National Standard-Performance Criteria for Radiobioassay Chris Alston