@article {Pina2016, title = {Towards a Standard Sampling Methodology on Online Social Networks: Collecting Global Trends on Twitter}, journal = {Applied Network Science}, volume = {1}, year = {2016}, pages = {3}, doi = {10.1007/s41109-016-0004-1}, url = {http://dx.doi.org/10.1007/s41109-016-0004-1}, author = {C. A. Pi{\~n}a-Garc{\'\i}a and Carlos Gershenson and J. Mario Siqueiros-Garc{\'\i}a} }