A device configured to receive a sentence that includes a plurality of words. The device is further configured to input the words into a machine learning model that is configured to output a first feature vector based on the words. The device is further configured to identify a keyword within the sentence and to determine that the keyword is an implicit reference to an item. The device is further configured to identify a second feature vector in a reference list that closest matches a numeric value of the first feature vector and to identify an explicit reference in the reference list that is associated with the second feature vector. The device is further configured to replace the keyword with the explicit reference in the sentence and to output the sentence that includes the first explicit reference.