Dictionary booksUrl = new Dictionary(); 请问如何遍历

Dictionary booksUrl = new Dictionary();
foreach (KeyValuePair ItemKey in booksUrl)
{
string booksUrlKey = ItemKey.Key;
Dictionary booksUrlValue = ItemKey.Value;
foreach (KeyValuePair ChildKey in booksUrlValue)
{
string tempDictionaryKey = ChildKey.Key;
string tempDictionaryValue = ChildKey.Value;
}
}