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: Autoradiographic evidence of estrogen binding sites in nuclei of diethylstilbesterol induced hamster renal carcinomas .
### Output Text:
Autoradiographic evidence of <span class="chemical">estrogen</span> binding sites in nuclei of <span class="chemical">diethylstilbesterol</span> induced hamster renal carcinomas . 