tras la pista de

= on the trail of, on the track of

Ex. Directories of publishers arranged to indicate the specialist fields in which the publish can be a boon to the imaginative librarian on the trail of some obscure source.

Ex. The article is entitled 'Cataloguing and classification at Bath University Library: on the track of white elephants and golden retrievers'.

* * *

= on the trail of, on the track of

Ex: Directories of publishers arranged to indicate the specialist fields in which the publish can be a boon to the imaginative librarian on the trail of some obscure source.

Ex: The article is entitled 'Cataloguing and classification at Bath University Library: on the track of white elephants and golden retrievers'.