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: However , there are two case reports that show tic - like symptoms , including motor and phonic variants , occurring during treatment with quetiapine or clozapine .
### Output Text:
However , there are two case reports that show tic - like symptoms , including motor and phonic variants , occurring during treatment with <span class="chemical">quetiapine</span> or <span class="chemical">clozapine</span> . 