Gray, P. (2013). Free to learn: Why unleashing the instinct to play will make our children happier, more self-reliant, and better students for life. Basic Books.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रGray, Peter. Free to Learn: Why Unleashing the Instinct to Play Will Make Our Children Happier, More Self-reliant, and Better Students for Life. New York: Basic Books, 2013.
एमएलए (8वां संस्करण) प्रशस्ति पत्रGray, Peter. Free to Learn: Why Unleashing the Instinct to Play Will Make Our Children Happier, More Self-reliant, and Better Students for Life. Basic Books, 2013.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.