Updated citation information

Author: lindonroberts

README.rst

@@ -23,7 +23,7 @@ Py-BOBYQA is a flexible package for solving bound-constrained general objective
 More details about Py-BOBYQA and its enhancements over BOBYQA can be found in our papers:
 
 1. Coralia Cartis, Jan Fiala, Benjamina Marteau and Lindon Roberts, `Improving the Flexibility and Robustness of Model-Based Derivative-Free Optimization Solvers <https://doi.org/10.1145/3338517>`_, *ACM Transactions on Mathematical Software*, 45:3 (2019), pp. 32:1-32:41 [`preprint <https://arxiv.org/abs/1804.00154>`_] 
-2. Coralia Cartis, Lindon Roberts and Oliver Sheridan-Methven, `Escaping local minima with derivative-free methods: a numerical investigation <https://arxiv.org/abs/1812.11343>`_, technical report, University of Oxford, (2018). 
+2. Coralia Cartis, Lindon Roberts and Oliver Sheridan-Methven, `Escaping local minima with derivative-free methods: a numerical investigation <https://doi.org/10.1080/02331934.2021.1883015>`_, *Optimization* (2021). [`preprint <https://arxiv.org/abs/1812.11343>`_] 
 
 Please cite [1] when using Py-BOBYQA for local optimization, and [1,2] when using Py-BOBYQA's global optimization heuristic functionality. For reproducibility of all figures, please feel free to contact the authors.