NIST recently paid the "Open Access" ransom for this paper, a pdf of which is attached. Please feel free to share it as you wish:
Newbury, D. E. and Ritchie, N. W. M., "Review: Performing Elemental Microanalysis with High Accuracy and High Precision by Scanning Electron Microscopy/Silicon Drift Detector Energy Dispersive X-ray Spectrometry (SEM/SDD-EDS)", J. Materials Science 50 (2015) 493-518.
Dale