Compiling parts of Festival code written in C++ in a stand-alone C++ program

Question

I am trying to use selective parts of the Festival code (written in C++) and trying to use them in my own C++ programs. Note that this question is not about using the Festival API but about functions within Festival that can be used directly.

The program I wrote takes in a C++ style string and tries to initialize an object of type EST_String (an internal implementation of the String class in Festival). I then try to print the object.

The code I have:

/*EST_String is a string implementation for the festival project.
 * This program simply takes in a C++-style string and returns an EST_String. 
 * This program is being used to test for makefiles etc.
 */

#include <iostream>
#include <EST_String.h>
#include <string>
#include <cstdlib>
using namespace std;

int main(int argc, char *argv[]) {

  if(argc != 2) {
    cout << "Correct usage: <binary> <string>" << endl;
    exit(5);
  }

  string word(argv[1]);
  EST_String e(word.c_str());  //init EST_String.

  cout << "C++ String = " << word << endl;
  cout << "EST_String = ";
  cout << e;

  return 0;
}  

I am trying to compile it (from the command line directly (no makefile at present)) like so:

g++ -I../../speech_tools/include -I../../speech_tools/base_class/string -L../../speech_tools/lib/ -lestbase -lncurses -lasound -leststring -lestools usingESTString.C -o usingESTString  

The error I get is:

/tmp/cczyGTfm.o: In function `main':
usingESTString.C:(.text+0x91): undefined reference to `EST_String::EST_String(char const*)'
/tmp/cczyGTfm.o: In function `EST_Chunk::operator--()':
usingESTString.C:(.text._ZN9EST_ChunkmmEv[EST_Chunk::operator--()]+0x3e): undefined reference to `EST_Chunk::~EST_Chunk()'
usingESTString.C:(.text._ZN9EST_ChunkmmEv[EST_Chunk::operator--()]+0x49): undefined reference to `EST_Chunk::operator delete(void*)'
collect2: ld returned 1 exit status  

How can I get the code to compile properly? Where am I going wrong?