English to Russian Science Medical: Health Care Research

I am translating a report on the use of narrative research in health care. This term is used in the section about the search strategy of sources reviewed in the report. Here are the examples:


Accordingly, three main principles guided the selection of review methodology:
(i) it must be centrally concerned with making sense of a complex literature, (ii) it must allow for iteration and progressive focusing, and (iii) it must enable a flexible trade-off between comprehensiveness (of the search phase) and intellectual depth (of the interpretation phase).

The author identified sources by beginning with a small selection of books and papers widely recognized as seminal in the field and then used various techniques (e.g. citation tracking or searching references of references) to expand from these while applying progressive focusing to limit the dataset.