In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: RESULTS : Ribavirin - induced anemia occurred in 18 ( 20 . 5 % ) patients during treatment .
### Output Text:
RESULTS : <span class="chemical">Ribavirin</span> - induced anemia occurred in 18 ( 20 . 5 % ) patients during treatment . 