added new reference

src/main.cpp

@@ -639,6 +639,8 @@ void cite()
 	cout << endl << INFO << "If you use NanoShaper please cite these works:";
 	cout << endl << CITE << "\tS. Decherchi, W. Rocchia, \"A general and Robust Ray-Casting-Based Algorithm for Triangulating Surfaces at the Nanoscale\"; PlosOne";
 	cout << endl << CITE << "\tlink: http://www.plosone.org/article/metrics/info%3Adoi%2F10.1371%2Fjournal.pone.0059744";
+	cout << endl << CITE << "\tS. Decherchi, A. Spitaleri, J. Stone, W. Rocchia, \"NanoShaper-VMD interface: computing and visualizing surfaces, pockets and channels in molecular systems\"; Bioinformatics";
+	cout << endl << CITE << "\t2019 Apr 1;35(7):1241-1243. doi: 10.1093/bioinformatics/bty761. PMID: 30169777; PMCID: PMC6449750.";
 	cout << endl;
 }