How do you traverse through double vectors.

Code:
for(int l = 0; l < myWordsInLetter->size(); l++)
{
	for(int m = 0; m < myWordsInLetter->at(l).size(); m++)
	{
		cout << myWordsInLetter->at(l).at(m);
	}
	cout << " ";
}
where myWordsInLetter is a vector<vector<string> >