GRUENWALD GEORGE. (1992). NEW PRODUCT DEVELOPMENT: RESPONDING TO MARKET DEMAND. NTC BUSINESS BOOKS.
Lua i Stíl Chicago (17ú heag.)GRUENWALD GEORGE. NEW PRODUCT DEVELOPMENT: RESPONDING TO MARKET DEMAND. U S A: NTC BUSINESS BOOKS, 1992.
Lua MLA (9ú heag.)GRUENWALD GEORGE. NEW PRODUCT DEVELOPMENT: RESPONDING TO MARKET DEMAND. NTC BUSINESS BOOKS, 1992.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.