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: HT included oestrogens , with or without progestogens , via oral , transdermal , subcutaneous or transnasal routes .
### Output Text:
HT included <span class="chemical">oestrogens</span> , with or without <span class="chemical">progestogens</span> , via oral , transdermal , subcutaneous or transnasal routes . 