Patricia Lauber. (1994). "Be a Friend to Trees (Let's-Read-and-Find-Out, Stage 2)" (Revised.). HarperCollins.
Chicago-viite (17. p.)Patricia Lauber. "Be a Friend to Trees (Let's-Read-and-Find-Out, Stage 2)". Revised. HarperCollins, 1994.
MLA-viite (9. p.)Patricia Lauber. "Be a Friend to Trees (Let's-Read-and-Find-Out, Stage 2)". Revised. HarperCollins, 1994.
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