Display referencing entity in panels
I know how to do it with Views and Panels modules.
First you need to create two Views:


First one is Lecture_view create a block and add fields you want to display(Title, body, most important - Content: Nid  and any other fields your Content type has).
Second one is Notes view, create same block but fields for notes to display, and also in a
Contextual filters menu add  new filter (Content) Content: Nid 


Now you should go to Lecture view and in Advanced menu, click on theme information link, and you need to create template file, find row with Field Content: Nid and create one of suggested fields, something like (views-view-field--conversations--page--nid-1.tpl.php) in /sites/all/themes/YOURTHEMENAME/views/YOURVIEWNAME(lecture_view--block)/YOURTEMPLATEFILE(views-view-field--conversations--page--nid-1.tpl.php) in this file you will past code from theme view, its something similar to 

&lt;?php print render($output); ?&gt;


you need to add one more thing embed that views:

&lt;?php print views_embed_view('notes', $display_id='default', $row-&gt;nid); ?&gt;


your contextual filter should work, and now you can add this view to your Panel to display, in Panel menu.

Maybe this is not the best way to do this