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: Patients participating in a randomised trial of anastrozole , tamoxifen alone or combined ( ATAC ) ( n = 94 ) and a group of women without breast cancer ( n = 35 ) completed a battery of neuropsychological measures .
### Output Text:
Patients participating in a randomised trial of <span class="chemical">anastrozole</span> , <span class="chemical">tamoxifen</span> alone or combined ( ATAC ) ( n = 94 ) and a group of women without breast cancer ( n = 35 ) completed a battery of neuropsychological measures . 