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: Side effects of hysterosalpingography with Dimer - X , Hexabrix , Vasurix polyvidone and Endografine in 142 consecutive patients , receiving one of the four tested media were evaluated from replies to postal questionnaires .
### Output Text:
Side effects of hysterosalpingography with <span class="chemical">Dimer - X</span> , <span class="chemical">Hexabrix</span> , <span class="chemical">Vasurix polyvidone</span> and <span class="chemical">Endografine</span> in 142 consecutive patients , receiving one of the four tested media were evaluated from replies to postal questionnaires . 