Schlechtriem, Peter: International Encyclopedia of Comparative Law. Under the Auspices of the International Association of Legal Science. Vol. 10.

Schlechtriem, Peter: International Encyclopedia of Comparative Law. Under the Auspices of the International Association of Legal Science. Vol. 10: Restitution, Unjust Enrichment and Negotiorum Gestio. Chap. 3. 5. 10. 11. 17. – Chap. 3: History of Restitution in Anglo-American Law. Chap. 5: Restitution of Benefits Conferred Without Obligation. Chap. 10: Payment of Another's Debt. Chap. 11: Adjustment Among Multiple Debtors. Chap. 17: Negotiorum Gestio