Fix references in tutorial 1

docs/tutorials/01_chemistry_hamiltonian.ipynb

@@ -145,7 +145,7 @@
    "source": [
     "We will use the [ffsim](https://github.com/qiskit-community/ffsim/tree/main) package to create and initialize the ansatz with `t2` and `t1` amplitudes computed above. Since our molecule has a closed-shell Hartree-Fock state, we will use the spin-balanced variant of the UCJ ansatz, [UCJOpSpinBalanced](https://qiskit-community.github.io/ffsim/api/ffsim.html#ffsim.UCJOpSpinBalanced).\n",
     "\n",
-    "As our target IBM hardware has a heavy-hex topology, we will adopt the _zig-zag_ pattern used in [2]() for qubit interactions. In this pattern, orbitals (represented by qubits) with the same spin are connected with a line topology (red and blue circles) where each line take a zig-zag shape due the heavy-hex connectivity of the target hardware. Again, due to the heavy-hex topology, orbitals for different spins have connections between every 4th orbital (0, 4, 8, etc.) (purple circles).\n",
+    "As our target IBM hardware has a heavy-hex topology, we will adopt the _zig-zag_ pattern used in [[2]](https://pubs.rsc.org/en/content/articlehtml/2023/sc/d3sc02516k) for qubit interactions. In this pattern, orbitals (represented by qubits) with the same spin are connected with a line topology (red and blue circles) where each line take a zig-zag shape due the heavy-hex connectivity of the target hardware. Again, due to the heavy-hex topology, orbitals for different spins have connections between every 4th orbital (0, 4, 8, etc.) (purple circles).\n",
     "\n",
     "![lucj_ansatz](../_static/images/lucj_ansatz_zig_zag_pattern.jpg)"
    ]