References – AN 1.616-627: Freedom From Death 
“If the task is to fully understand and you have an affinity for understanding form, does that affect how you understand the other aggregates?” Answered by Ajahn Karuṇadhammo. [Noble Truth of Suffering] [Body/form] [Aggregates] // [Thai Forest Tradition] [Mindfulness of body] [Insight meditation]
Sutta: AN 1.616: Mindfulness directed to the body and the deathless.
The Fourth Foundation of Mindfulness [2013], Session 27, Excerpt 5
Readings from Body Contemplation: A Study Guide by Ajahn Ṭhānissaro. Read by Ajahn Karuṇadhammo. [Mindfulness of body]
AN 4.184: Janussonī; AN 10.60: Girimananda; SN 35.247: Six Animals; AN 4.45: Rohitassa; Thag 1.104: Khitaka.
Dhp 259, Dhp 299, Dhp 46; Ud 3.5.
AN 1.575 and onward, Mindfulness immersed in the body (SuttaCentral numbering).
AN 1.616 and onward, Deathless (SuttaCentral numbering).