With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Nigeria is the most populous country in the world.
text_B: Frederick Leypoldt -LRB- 17 November 1835 , in Stuttgart , Germany -- 31 March 1884 , in New York City -RRB- was a bibliographer , the founder of Library Journal , Publisher 's Weekly , Index Medicus and other publications .. Stuttgart. Stuttgart. bibliographer. bibliographer. Library Journal. Library Journal. Index Medicus. Index Medicus
not_related.