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 : In a population - based study in 513 naturally postmenopausal women aged 54 - 67 years , we studied the association between self - reported intramuscularly administered high - dose estrogen - testosterone therapy ( estradiol - and testosterone esters ) and aortic atherosclerosis .
### Output Text:
METHODS : In a population - based study in 513 naturally postmenopausal women aged 54 - 67 years , we studied the association between self - reported intramuscularly administered high - dose <span class="chemical">estrogen</span> - <span class="chemical">testosterone</span> therapy ( <span class="chemical">estradiol - and testosterone esters</span> ) and aortic atherosclerosis . 