1. National Institute of Standards and Technology 1992 Certificate of analysis, standard reference material 611, trace elements in a glass matrix, nominal element concentration 500 mg/kg
2. National Institute of Standards and Technology 1992 Certificate of analysis, standard reference material 612, trace elements in a glass matrix, nominal element concentration 50 mg/kg
3. National Institute of Standards and Technology 1992 Certificate of analysis, standard reference material 614, trace elements in a glass matrix, nominal element concentration 1 mg/kg
4. National Institute of Standards and Technology 1990 Certificate of analysis, standard reference material 1834, fused simulated ore for X-ray fluorescence spectrometry