There are multiple ways you can handle this, and it all depends on either how much description space you have or how many entries you have left to fill. There's really no right or wrong way to do it.
1) You can group the poster presentations and the oral presentation together. List the conference you presented at, the title of your presentation, the date, and any other pertinent information
2) You can group the papers and abstract together and give the citations in the description. If there's not enough room, you can either split them up into two entries, or you can do #3...
3) Include the citations for the papers with the relevant research entries. This might not be feasible if all of your papers and presentations came from the same research, and in which case I would go with options #1 and #2, unless the research is one of your most meaningful experiences, in which case you have a larger description to work with. But if you have multiple work/activities entries for research, you can include the respective publications in the descriptions there.
