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: CONCLUSIONS : A comparison of frequency of adverse reactions to indocyanine green with the previously reported frequency of such reactions to fluorescein sodium indicated that indocyanine green is a safe as fluorescein for use in angiography .
### Output Text:
CONCLUSIONS : A comparison of frequency of adverse reactions to <span class="chemical">indocyanine green</span> with the previously reported frequency of such reactions to <span class="chemical">fluorescein sodium</span> indicated that <span class="chemical">indocyanine green</span> is a safe as <span class="chemical">fluorescein</span> for use in angiography . 