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 the 59 cases , 26 ( 44 % ) had a fatal outcome , compared to 136 ( 25 % ) among the non - warfarin patients ( p < 0 . 01 ) .
### Output Text:
Of the 59 cases , 26 ( 44 % ) had a fatal outcome , compared to 136 ( 25 % ) among the non - <span class="chemical">warfarin</span> patients ( p < 0 . 01 ) . 