Well, your question popped two questions in my mind. First, if you are asking how triple pointers can be implemented and used(the syntax) and second, if you are interested in knowing the practical utility of triple pointers. The former has been vividly answered by @rude , for the latter version ( i suppose this can be a good question too :P ) here I go.
For example, let's take a char pointer so that char pointer can point to a string, better say a sentence. Now imagine many such pointers, each pointing to a sentence.
Next, think of a pointer that points to the collection(array) of all the above pointers. It will point to a collection of sentences and hence it is analogous to a page.
And here comes the third pointer which can point to the collection of all page pointers and represent a chapter.
Something like this :
Add another pointer (fourth pointer) and you will have a book !