鑽故紙堆 [钻－纸－]

Jyutping zyun1 gu3 zi2 deoi1
Pinyin zuān gù zhǐ duī

Definitions (CC-CEDICT)
  1. to dig into piles of outdated writings (idiom); to study old books and papers
Examples (Wiktionary)
  1. Mandarin
    钻故纸堆
    鑽故紙堆
    zuān gù zhǐ duī
    • to delve into old books