TY - RPRT TI - Certification of standard reference material SRM2687a, Portland cement clinker AU - Stutzman, Paul AU - Heckert, Alan PY - 2019 PB - National Institute of Standards and Technology CY - Gaithersburg, MD SN - NIST SP 260-195 DO - 10.6028/NIST.SP.260-195 ER -