poring over maps of the Russian Empire.
It will take several more months to pore through the volumes of documents.
to pore: If you pore over or through information, la examinas y la estudias con mucho cuidado.
1. (foll by over) Examinar o estudiar minuciosamente (un libro, mapa, etc.). Leer o estudiar detenidamente
to pore over a book
I pored over the documents for several hours
2. (foll by over, on, or upon) Pensar profundamente (sobre). Pensar profunda y exhaustivamente; reflexionar con...
he pored on the question of their future