Private Development Corporation of the Philippines. (1973). The portland cement industry. s.n.].
Citazione stile Chigago Style (17a edizione)Private Development Corporation of the Philippines. The Portland Cement Industry. [Makati, Rizal: s.n.], 1973.
Citatione MLA (9a ed.)Private Development Corporation of the Philippines. The Portland Cement Industry. s.n.], 1973.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.