Abbreviation for:
Huáng Xiànián 黃夏年, ed. Mínguó fójiào qíkān wénxiàn jíchéng 民國佛教期刊文獻集成 (Complete Collection of Republican-Era Buddhist Periodical Literature), 209 vols. Beijing: Quánguó túshūguǎn 全國圖書館, 2006.
There is also a supplement of 83 volumes. See MFQB.
The Digital Archives at Dharma Drum Buddhist College has developed and maintains a search tool for the entire collection, which covers both sets.
Here is the PDF of an essay that discusses the structure of this collection, the history of its compilation, and tips on how to use it.