Gaya APA

W., S, F. (2010). Improving students writing skill using four square writing method (A collanorative action research . : Universitas Sebelas Maret.

Gaya MLA

W., SITI, FATIMAH. "Improving students writing skill using four square writing method (A collanorative action research". : Universitas Sebelas Maret, 2010. Skripsi.