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: AZT - induced peripheral anaemia in the face of increased numbers of BFU - e and increased levels of plasma EPO suggest a lesion in terminal differentiation .
### Output Text:
<span class="chemical">AZT</span> - induced peripheral anaemia in the face of increased numbers of BFU - e and increased levels of plasma EPO suggest a lesion in terminal differentiation . 