grey literature

基本解释

And 19th century literature was transformed by Anne's Agnes Grey, Emily's Wuthering Heights, and Charlotte's Jane Eyre.
安妮的艾格妮斯·格雷，艾米丽的呼啸山庄，和夏洛特的简爱极大改变了19世纪的文学创作。
piggywang2007.blog.163.com
To review systematically research studies, which have investigated the impact of grey literature in meta-analyses of randomized trials of health care interventions.
凡探索灰色文献对随机临床试验统合分析结果之影响的相关研究，收集并进行系统性的回顾。
This means that those carrying out systematic reviews need to search for trials in both the published and grey literature in order to help minimise the effects of publication bias in their review.
其意涵为：文献回顾应包含已出版的及灰色文献，以将出版偏差的影响减少到最低的程度。

In my opinion, you are absolutely correct in calling out the IPC for lowering grey literature standards rather than raising them.
FORBES: The Self Corruption of Climate Science
The information pool consists of monographs, series, journals, grey literature and databases.
UNESCO: Centro de Recursos Documentales e Informaticos (CREDI)
Still, most would not see the Gray Lady as grey literature.
ECONOMIST: Rajendra Pachauri and the IPCC