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: A case of fatal aplastic anemia due to carbamazepine treatment in an epileptic woman is reported .
### Output Text:
A case of fatal aplastic anemia due to <span class="chemical">carbamazepine</span> treatment in an epileptic woman is reported . 