Costelloe, Daniel
Legal consequences of peremptory norms in international law
Cambridge University Press, 2017
 Buku Teks
Research handbook on international conflict and security law : jus ad bellum, jus in bello and jus post bellum
edited by Nigel D. White, Christian Henderson
Edward Elgar Publishing, 2013
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Elliot, Catherine
Contract law
Longman , 2001
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McKendrick, Ewan
Contract law
Macmillan, 1994
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Brown, Ian
Law of contract
Blackstone, 1994
 Buku Teks