Lewis, H. (1992). The consultant's complete proposal manual. PTRC Research & Education Services.
Lua i Stíl Chicago (17ú heag.)Lewis, Harold. The Consultant's Complete Proposal Manual. London: PTRC Research & Education Services, 1992.
Lua MLA (9ú heag.)Lewis, Harold. The Consultant's Complete Proposal Manual. PTRC Research & Education Services, 1992.
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