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: Coagulation ( prothrombin time [ PT ] , activated partial thromboplastin time [ APPT ] , fibrinogen concentration , and antithrombin III [ AT III ] ) was comparable between the two groups .
### Output Text:
Coagulation ( prothrombin time [ PT ] , activated partial thromboplastin time [ APPT ] , fibrinogen concentration , and antithrombin III [ AT III ] ) was comparable between the two groups . 