Nevalainen, Terttu
Edinburgh University Press, 2006
Buku Teks SO
edited by Irma Taavitsainen and Paivi Pahta
Cambridge University Press, 2011
Buku Teks SO
Plucknett, Theodore Frank Thomas
At The University Press, 1958
Buku Teks SO
Schwyzer, Philip
Cambridge University Press, 2009
eBooks
Hewitt, Douglas
Longman, Green, 1992
Buku Teks SO