When screen reader users need to back track pages to re-find previously visited content, they are forced to listen to some portion of each unwanted page to recognize it. This makes aural back navigation inefficient, especially on large websites. To address this problem, we introduce topic- and list-based back: two navigation strategies that provide back browsing shortcuts by leveraging the conceptual structure of content-rich websites. Both are manifested in Webtime, an accessible website on the history of the Web. A controlled study (N=10) conducted at the Indiana School for the Blind and Visually Impaired compared topic- and list-based back to traditional back mechanisms while participants completed fact-finding tasks. Topic- and list-based back significantly decreased time-on-task and number of backtracked pages; the navigation shortcuts were also associated with positive improvements in perceived cognitive effort and navigation experience. The proposed strategies can operate as a supplement to current back mechanisms in information-rich websites.