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: Haloperidol induced a significantly higher incidence ( p < 0 . 001 ) of akathisia ( 33 . 3 % versus 5 . 9 % ) , tremor ( 30 . 3 % versus 7 . 8 % ) , and extrapyramidal syndrome ( 35 . 4 % versus 5 . 9 % ) than quetiapine .
### Output Text:
<span class="chemical">Haloperidol</span> induced a significantly higher incidence ( p < 0 . 001 ) of akathisia ( 33 . 3 % versus 5 . 9 % ) , tremor ( 30 . 3 % versus 7 . 8 % ) , and extrapyramidal syndrome ( 35 . 4 % versus 5 . 9 % ) than <span class="chemical">quetiapine</span> . 