Here is the link to this week's study and discussion:

http://www.ssnet.org/lessons/13b/less06.html

Does anybody know who wrote the book of Jonah?

Although the book itself nowhere states that Jonah was the author, the traditional view has been that he was. Many modern scholars have favored a postexilic authorship though not necessarily denying the historicity of Jonah. However, the arguments they advance, such as the presence of Aramaisms, are inconclusive. The study of Ugaritic has demonstrated the antiquity of many forms and words that were formerly held to belong to a much later date (see on Ps. 2:12; see Vol. III, pp. 618, 619). The use of the third person is likewise an insufficient argument, inasmuch as not a few ancient writers, such as Xenophon, Caesar, and others employed this method. Bible writers, too, at times used this method (Isa. 7:3; 20:2; Jer. 20:1, 3; 26:7; Dan. 1:6–11, 17, 19, 21; Dan. 2:14–20; etc.; see on Ezra 7:28).

From Keil & Delitzsche:

“What could Jonah say to this? He was obliged to keep silence, defeated, as it were, by his own sentence” (Luther). The history, therefore, breaks off with these words of God, to which Jonah could make no reply, because the object of the book was now attained, - namely, to give the Israelites an insight into the true nature of the compassion of the Lord, which embraces all nations with equal love.