Wills, I. R. (2007). Economics and the environment: A signalling and incentives approach (2nd ed.). Allen & Unwin.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रWills, Ian R. Economics and the Environment: A Signalling and Incentives Approach. 2nd ed. St. Leonards, NSW: Allen & Unwin, 2007.
एमएलए (8वां संस्करण) प्रशस्ति पत्रWills, Ian R. Economics and the Environment: A Signalling and Incentives Approach. 2nd ed. Allen & Unwin, 2007.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.