search for string of one column in another column

import pandas as pd
df = pd.DataFrame({'_id':'Y100','paper_title':'abc','reference':['sdfaqdtsdf','sdfkdsjgkgg','fjafjhafkj']},{'_id':'Y101','paper_title':'efg','reference':['cdfabctzdi','vjedbvjbdjk','efhlghjehg']},{'_id':'Y102','paper_title':'lmn','reference':['zdfabdtssf','boblfbjbsfb','qwhfefqwfob']},........)
df.set_index(['_id','paper_title'], inplace = True)
print(df)
Out[1]:
_id   paper_title   reference
Y100   abc          sdfaqdtsdf
       abc          sdfklmngkgg
       abc          fjafefgfkj
Y101   efg          cdfabdtzdi
       efg          vjedbvjbdjk
       efg          efhlmnjehg
Y102   lmn          zdfabdtssf
       lmn          boblfbjbsfb
       lmn          qwhfefqwfob

Expected results:
_id   paper_title    reference                                   this_paper_presented_in
Y100   abc          ['sdfaqdtsdf','sdfklmngkgg','fjafefgfkj']     [Y101,Y102]
Y101   efg          ['cdfabdtzdi','vjedbvjbdjk','efhlmnjehg']     [Y102]
Y102   lmn          ['zdfavdtssf','boblfbjbsfb','qwhfefqwfob']    [None(if this paper_title not present in column reference)]

SideNote:
Same paper_title can not be present in it's own reference row i.e (Y100 paper_title can not be present in same reference)