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: Careful use of epsilon - aminocaproic acid therapy is recommended .
### Output Text:
Careful use of <span class="chemical">epsilon - aminocaproic acid</span> therapy is recommended . 