นามสกุลของผู้เขียนบทความเรื่อง "Binders Unbound" คืออะไร?
What are the last names of the author of the paper titled "Binders Unbound"?
authorship = pd.DataFrame(columns=['authid', 'paperid']); authors = pd.DataFrame(columns=['lname', 'authid']); papers = pd.DataFrame(columns=['paperid', 'title'])
authors.loc[authors['authid'].isin(authorship.loc[papers[papers['title'] == 'Binders Unbound']['paperid'], 'authid']), 'lname']