Question: what were the baselines?
Answer: Rank by the number of times a citation is mentioned in the document,  Rank by the number of times the citation is cited in the literature (citation impact). , Rank using Google Scholar Related Articles., Rank by the TF*IDF weighted cosine similarity. , ank using a learning-to-rank model trained on text similarity rankings
Alternative answer: (1) Rank by the number of times a citation is mentioned in the document., (2) Rank by the number of times the citation is cited in the literature (citation impact)., (3) Rank using Google Scholar Related Articles., (4) Rank by the TF*IDF weighted cosine similarity., (5) Rank using a learning-to-rank model trained on text similarity rankings.