Pearls can be used to good effect in the orientation phase if you do not know the right search terms.
You start a search and then see if the (list of) results, the websites or documents themselves, contain other and perhaps better search terms.
Example from the NHL Stenden-catalogue:
You type the word tweedetaalverwerving at ‘all words’. If you look at the description of the Handbook of Dutch as a second language, you will also find: Dutch for non-native speakers. You can use this to search further.
You can also see which author appears frequently in your first search results. This is probably an important author within the respective field. Use the author’s name in the Author field to further search for publications.