In this theory I treat the historical work as what it most manifestly is: a verbal structure in the form of a narrative prose discourse. Histories (and philosophies of history as well) combine a certain amount of "data", theoretical concepts for "explaining" these data, and a narrative structure for their presentation as an icon of sets of events presumed to have occured in times past. In addition, I maintain, they contain a deep structural content which is generally poetic, and specifically linguistic, in nature, and which serves as the precritically accepted paradigm of what a distinctively "historical" explanation should be.
Source: Hayden White: Metahistory, p. ix.
I would like to ask you to tell me what noun the pronoun "they" represents in the bold sentence. The most logic possibility seems to be "historical work" but it is in the preceding sentence in the singular form so I hesitate.