(2018b,c) also falls in this category, as the questions were written using the reference summary.
summarization datasets are limited to a single reference summary per document (Sandhaus, 2008;Hermann et al., 2015;Grusky et al., 2018;Narayan et al., 2018b) thus evaluations using them is prone to reference bias (Louis and Nenkova, 2013), also a known issue in machine translation evaluation (Fomicheva and Specia, 2016).