import re
 
test_text = ['Sentence 1 (Author, 2019).',
             'Sentence 2 (Another Author, 2020)',
             'Sentence 3 (First Author & Second Author, 2018)',
             'Sentence 4 (Author, 2019; Another Author, 2020; Fourth Author, 2017)']
 
test_list = []
pattern = r'\(([^()]+)\)'
 
for elem in test_text:
    temp = []
    for splitOne in re.search(pattern, elem).group(1).split(";"):
        for splitTwo in splitOne.split(":"):
            temp.append(splitTwo.strip())
    test_list.append(temp)
 
print("FULL LIST OF PULL:\n", test_list)

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