파이썬으로 논문 내용을 문자마다 구분지으려고 하는데 어려움이 있습니다

# -*- coding: utf-8 -*-
 
# [3] 엔 이름과 논문제목 사이에 ":" 대신 "." 이 있어서 전체적으로 규칙성을 부여하기 힘드므로
# 원본자료를 "." 대신 ":" 으로 수정을 했습니다.
kdata = """\
[1] B. Aditya, G. Bhalotia, S. Chakrabarti, A. Hulgeri, C. Nakhe, P. Parag, and S. Sudarshan. Banks: browsing and keyword searching in relational databases. In Proc. VLDB Conf., pages 1083–1086. VLDB Endowment, 2002.
 
[2] S. Agrawal, S. Chaudhuri, and G. Das. Dbxplorer: A system for keyword-based search over relational databases. In Proc. ICDE Conf., page 5, Washington, DC, USA, 2002. IEEE Computer Society.
 
[3] S. Basu Roy, H. Wang, G. Das, U. Nambiar, and M. Mohania: Minimum-effort driven dynamic faceted search in structured databases. In Proc. CIKM, pages 13–22, 2008.
"""
 
import re
 
klines = kdata.split("\n")
 
kname = []
ksubject = []
kyear = []
 
def kname_search(s):
    p = re.search("\].+(?=:)", s)
    kname.append(p.group(0)[2:])
 
def ksubject_search(s):
    p = re.search("(?<=: ).+[a-z][.]", s)
    pp = p.group(0)
    ppp = pp.split(".")[0]
    ksubject.append(ppp)
 
def kyear_search(i):
    p = re.search("19[0-9][0-9]|20[0-9][0-9]", i)
    kyear.append(p.group(0))
 
for line in klines:
    if len(line) != 0:
        kname_search(line)
 
for line in klines:
    if len(line) != 0:
        ksubject_search(line)
 
for line in klines:
    if len(line) != 0:
        kyear_search(line)
 
for x, y, z in zip(kyear, ksubject, kname):
    print(x, "\t", y, "\t", z)