Sentence:  In the present work whole sera have been fractionated by chromatography on DEAE-cellulose using single gradients similar to those <WSD>described</WSD> by Sober and Peterson , and certain chemical and serological properties of the fractions containing antibodies of the ABO and Rh systems have been described . 
Meaning of the word marked with <WSD> tags:  to give an account or representation of in words