1 adverbs to describe how to impeccables

The compilations began with the great geographical encyclopaedia of Ku Yen-wu (1613-1682), and attained their climax in the gigantic eighteenth-century encyclopaedia T'u-shu chi-ch'eng, scientifically impeccable in the accuracy of its references to sources.

1 adverbs to describe how to  impeccables  - Adverbs for  impeccables