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: The recommended starting dose for Phase II trials is 60 mg / m2 IV bolus every 3 weeks .
### Output Text:
The recommended starting dose for Phase II trials is 60 mg / m2 IV bolus every 3 weeks . 