Patricia Lauber. (1994). "Be a Friend to Trees (Let's-Read-and-Find-Out, Stage 2)" (Revised.). HarperCollins.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रPatricia Lauber. "Be a Friend to Trees (Let's-Read-and-Find-Out, Stage 2)". Revised. HarperCollins, 1994.
एमएलए (9वां संस्करण) प्रशस्ति पत्रPatricia Lauber. "Be a Friend to Trees (Let's-Read-and-Find-Out, Stage 2)". Revised. HarperCollins, 1994.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.