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: Tamoxifen ( TAM ) , the antiestrogenic drug most widely prescribed in the chemotherapy of breast cancer , induces changes in normal discoid shape of erythrocytes and hemolytic anemia .
### Output Text:
<span class="chemical">Tamoxifen</span> ( <span class="chemical">TAM</span> ) , the antiestrogenic drug most widely prescribed in the chemotherapy of breast cancer , induces changes in normal discoid shape of erythrocytes and hemolytic anemia . 