Who were the wives of Cain and Seth?

Here is the question I have received:

When the world was created, Adam and Eve had two boys: Cain and Abel. Cain killed Abel having well known reasons. Cain was chased to the wilderness where he met his wife and had sons and daughters. The question is who was this woman, since at that time Eve was the only one mentioned. The same thing is true with Seth, the next son after those 2, who also met his woman. Is it an gap or it is considered that it is not important to mention about these women?

Cain, Abel and Seth are not the only children of Adam and Eve. The Bible says:

When Adam had lived one hundred and thirty years, he became the father of a son in his own likeness, according to his image, and named him Seth. Then the days of Adam after he became the father of Seth were eight hundred years, and he had other sons and daughters. So all the days that Adam lived were nine hundred and thirty years, and he died. (Genesis 5:3-5)(NASB)

Because the events are described one after another, we are sometimes tempted to believe that little time has passed from one event to another. This passage shows that it was not so. So, those daughters who were born to Adam and Eve became the wives of Cain, Seth and their other sons. From them people have multiplied and were spread throughout the earth.

Translated by Felicia Djugostran