Translating the Setge de Calanda article from Catalan to Spanish, two different references are added as "" in the translation. The issue happens with both Apertium and Google Translate.
This quick link provides an easy to reproduce example (based on an excerpt with the problematic references). Note that the references are shown as  nd  in the source paragraph but they become  and  when they are added to the translation. Example using Google Translate: