In order to create a collapsible accordion, you will have to write code in the Source editor. The easiest way to do this is to create the content you want as you normally would, making the things you want to be buttons a correct header (as appropriate for your content). After you write the content and properly apply the code, this is what it would look like / how it would work:
Here is a working example of what this looks like:
Miller, G. A., Galanter, E., & Pribram, K. H. (1960). Plans and the structure of behavior. Henry Holt and Co. https://psycnet.apa.org/doi/10.1037/10039-000
For a selection from an edited book that has different authors for different chapters.
Valetk, H. A. (2006). A federal law criminalizing cyberstalking is needed. In J. Carroll (Ed.), Privacy (pp. 214-219). Greenhaven.
The code for an accordion that uses H3s as the button label is included here. If you need to use H4s as appropriate, you will need to change each instance of H3 to H4 (shown with black highlight).
/* This starts the accordion*/
<div aria-multiselectable="false" class="panel-group" id="accordion" role="tablist">
/* This starts one panel */
<div class="panel panel-default">
/* Things you MUST change to match for each additional panel are highlighted.*/
<div class="panel-heading" id="tab1" role="tab">
<h3 class="panel-title"><a aria-controls="tab1-panel" aria-expanded="false" data-parent="#accordion" data-toggle="collapse" href="#tab1-panel" role="button">
This is where you type what you want on the button that will expand.
<div aria-labelledby="head_tab1" class="panel-collapse collapse" id="tab1-panel" role="tabpanel">
This is where you place the content that you want to be displayed when you click on the button to expand that section.