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: METHODS : From the Danish National Register of Patients ( NRP ) , 1996 to 1998 , the records of 1 . 1 million Danish women , ages 15 to 44 years , were searched for evidence of VTE .
### Output Text:
METHODS : From the Danish National Register of Patients ( NRP ) , 1996 to 1998 , the records of 1 . 1 million Danish women , ages 15 to 44 years , were searched for evidence of VTE . 