# Applying systematic review search methods to the grey literature: a case study examining guidelines for school-based breakfast programs in Canada

## TL;DR

This paper presents a systematic method for searching grey literature, demonstrated through a case study on Canadian school breakfast program guidelines.

## Contribution

A new systematic grey literature search method combining databases, Google, websites, and expert consultation is proposed and tested.

## Key findings

- The four-strategy search method yielded 302 items, with 15 meeting eligibility criteria for inclusion.
- The method proved manageable, comprehensive, and adaptable for other grey literature searches.
- High-level findings from the case study on breakfast program guidelines are summarized.

## Abstract

Grey literature is an important source of information for large-scale review syntheses. However, there are many characteristics of grey literature that make it difficult to search systematically. Further, there is no ‘gold standard’ for rigorous systematic grey literature search methods and few resources on how to conduct this type of search. This paper describes systematic review search methods that were developed and applied to complete a case study systematic review of grey literature that examined guidelines for school-based breakfast programs in Canada.

A grey literature search plan was developed to incorporate four different searching strategies: (1) grey literature databases, (2) customized Google search engines, (3) targeted websites, and (4) consultation with contact experts. These complementary strategies were used to minimize the risk of omitting relevant sources. Since abstracts are often unavailable in grey literature documents, items’ abstracts, executive summaries, or table of contents (whichever was available) were screened. Screening of publications’ full-text followed. Data were extracted on the organization, year published, who they were developed by, intended audience, goal/objectives of document, sources of evidence/resources cited, meals mentioned in the guidelines, and recommendations for program delivery.

The search strategies for identifying and screening publications for inclusion in the case study review was found to be manageable, comprehensive, and intuitive when applied in practice. The four search strategies of the grey literature search plan yielded 302 potentially relevant items for screening. Following the screening process, 15 publications that met all eligibility criteria remained and were included in the case study systematic review. The high-level findings of the case study systematic review are briefly described.

This article demonstrated a feasible and seemingly robust method for applying systematic search strategies to identify web-based resources in the grey literature. The search strategy we developed and tested is amenable to adaptation to identify other types of grey literature from other disciplines and answering a wide range of research questions. This method should be further adapted and tested in future research syntheses.

The online version of this article (doi:10.1186/s13643-015-0125-0) contains supplementary material, which is available to authorized users.