Spence, W. P. (1973). Drafting technology and practice. Peoria, ILL : Bennett.
Citazione stile Chigago Style (17a edizione)Spence, William Perkins. Drafting Technology and Practice. Peoria, ILL : Bennett, 1973.
Citatione MLA (9a ed.)Spence, William Perkins. Drafting Technology and Practice. Peoria, ILL : Bennett, 1973.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.