Directory Plugin - Category Thumbnail resize


I want to change the thumbnail size for the listings on a Category page.

Default is 50 x 26

<div class="entry-summary">
<img width="50" height="26" src="" class="alignleft wp-post-image" alt="logo" title="logo" />

I could not find where to make the change. It seems like a style change but i could not find it in the style sheets.