References – Snp 4.11: Quarrels and Disputes 
Discussion of the meaning of papañca in AN 8.30 and various other suttas. [Pāli] [Translation] [Proliferation] [Perception] // [Great disciples] [Liberation] [Conditionality] [Directed thought and evaluation] [Language]
Suttas: Snp 4.11: Kalahavivāda Sutta and DN 21: Sakkapañha Sutta in which papañca precedes thinking.
Reference: Skill in Questions by Ajahn Ṭhānissaro, p. 85.
Suttas: MN 19: Dvedhāvitakka Sutta; MN 20: Vitakkasaṇṭhāna Sutta.
Reference: Concept and Reality in Early Buddhist Thought by Bhikkhu Ñāṇananda
The Four Foundations of Mindfulness [2015], Session 48, Excerpt 1
Readings by Ajahn Amaro:
The Island by Ajahn Pasanno and Ajahn Amaro, Chapter 8, pp. 141-142:
Stillness Flowing by Ajahn Jayasaro, pp. 90-91.
Sutta: Snp 4.11 (Venerable H. Saddhatissa translation).