1968 Flux measurements at the centers of stellar H- and K-lines. Astrophys. J. 153:221–34.
1970 Widths of Ca II chromospheric emission lines as a measure of stellar luminosity. Proc. Astron. Soc. Pac. 82:865–77.
With R.Woolley. Calcium emission intensities as indicators of stellar age. Mon. Not. Roy. Astron. Soc. 148:463–475.
1978 Chromospheric variations in main sequence stars. Astrophys. J. 226:379– 96. (Henry Norris Russell Lecture)
1982 Photoelectric measures of chromospheric H and K and He in giant stars. Astrophys. J. 257:179–92.