Uncheck all types of information except Proposals, abstracts, and schedules.
Click More Options.
If more than one table is found, a page will be displayed where you will need to choose a table. Choose one that mentions abstracts in the name, unless you already know that a table has abstracts.
Click Specify Additional Parameters.
A new page is displayed showing all the available columns for the table.
Make sure the checkbox in the leftmost column for the abstract row is on.
Change the operator to "=" or "!=", and enter a search term in the left text box. You can use '*' or '%' as a multi-character wildcard. There is an automatic wildcard added to the end so you can just enter a partial keyword.