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: Of 13 documented fractures , 3 occurred after risperidone and SSRIs were started , and none occurred in patients with hyperprolactinemia .
### Output Text:
Of 13 documented fractures , 3 occurred after <span class="chemical">risperidone</span> and SSRIs were started , and none occurred in patients with hyperprolactinemia . 