Ruggedness tests on the high performance liquid chromatography assay of the United States Pharmacopoeia 23 for tetracycline.HCl: comparison of different columns in an interlaboratory approach, Heyden, Y.V., Massart D.L., Zhu Y., Hoogmartens J., and de Beer J.L. , J.Pharm.Biomed.Anal., 0/6/1996, Volume 14, Issue 8-10, Number 1326, p.1313 - 1326, (1996)