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: We present a case of yellow phosphorus poisoning in which a patient presented with florid clinical features of cholestasis highlighting the fact that cholestasis can rarely be a presenting feature of yellow phosphorus hepatotoxicity .
### Output Text:
We present a case of yellow <span class="chemical">phosphorus</span> poisoning in which a patient presented with florid clinical features of cholestasis highlighting the fact that cholestasis can rarely be a presenting feature of yellow <span class="chemical">phosphorus</span> hepatotoxicity . 