The primary text is the introduction to Shaarei Yosher by Rav Shimon Shop. The introduction with translation is chapter 1 of my book Widen Your Tent, and the chapter is available as a PDF, linked to on the source sheet.
This week we discussed material in section 1.2 and 1.3 of Widen Your Tent. (Paragraphs 2 & 3 in the original edition of Shaarei Yosher.
More resources for these chaburos at https://thekloiz.aishdas.org