Updated some Old links and Added some links in "02_portfolio_diversification.ipynb"

tutorials/finance/02_portfolio_diversification.ipynb

@@ -156,13 +156,13 @@
     "\n",
     "[1] G. Cornuejols, M. L. Fisher, and G. L. Nemhauser, *Location of bank accounts to optimize float: an analytical study of exact and approximate algorithms*, Management Science, vol. 23(8), 1997\n",
     "\n",
-    "[2] E. Farhi, J. Goldstone, S. Gutmann e-print arXiv 1411.4028, 2014\n",
+    "[2] E. Farhi, J. Goldstone, S. Gutmann e-print [arXiv 1411.4028, 2014](https://arxiv.org/abs/1411.4028)\n",
     "\n",
-    "[3] G. Cornuejols and R. Tutuncu, *Optimization methods in finance*, 2006\n",
+    "[3] G. Cornuejols and R. Tutuncu, [Optimization methods in finance](http://web.math.ku.dk/~rolf/CT_FinOpt.pdf), 2006\n",
     "\n",
     "[4] DJ. Berndt and J. Clifford, *Using dynamic time warping to find patterns in time series*. In KDD workshop 1994  (Vol. 10, No. 16, pp. 359-370).\n",
     "\n",
-    "[5] https://github.com/Qiskit/qiskit-tutorial/blob/master/qiskit/aqua/optimization/maxcut_and_tsp.ipynb"
+    "[5] [6_examples_max_cut_and_tsp.ipynb](https://github.com/Qiskit/qiskit-tutorials/blob/master/tutorials/optimization/6_examples_max_cut_and_tsp.ipynb)"
    ]
   },
   {