The use of grey literature in the agricultural economics field: a quantitative analysis.

Despite the increasing attention to GL a number of methodological issues remain unsolved, basically standards of presentations and indicators for measuring GL use. The main aim of this paper is to study the use of GL in agricultural economics. This field of agricultural science is an interesting point of observation because it represents a social science (economics) in an applied context (agricultural). Previous studies showed that all agricultural research fields are strongly connected to agricultural economics. Current research in this field reveals the usage of various types of GL document. We identify different patterns of GL use through the analysis of citations fo GL in bibliographic references for a source sample consisting of core journals. Cited GL documents are described by their type (report, thesis, preprint, etc.), producer and publication date. Furthermore, based on their type, they are classified into three categories (dark - medium - light grey documents) in order to account for different tones of grey in GL, by which we mean different levels of availability and accessibility. Moreover, we estimate the coverage of each of theses three categories of GL documents for specialised libraries and Internet.