diff --git a/public/js/peGuide.js b/public/js/peGuide.js
index a0a5937..8298140 100644
--- a/public/js/peGuide.js
+++ b/public/js/peGuide.js
@@ -1,6 +1,12 @@
 // ============================================================
 // PHYSICAL EXAM GUIDE — step-by-step OSCE reference + report generator
 // ============================================================
+// Sources for the exam content:
+//   - Bates' Guide to Physical Examination, 13th edition (technique)
+//   - Nelson Textbook of Pediatrics, 22nd edition (age-specific content)
+//   - Hutchison's Clinical Methods, 25th edition (systematic approach)
+//   - Developmental reflex timing: Fenichel Clinical Pediatric Neurology, 8th ed
+//
 // Data model:
 //   PE_DATA[ageGroup][system] = { overview, components: [{ name, steps: [{label, method, normal}], abnormalHints }] }
 // Each step has its own Normal / Abnormal / Skip toggle so the physician