df_null_dates = csv_manager.concat_csv(all_csv_null_dates)
df_wrong_dates = csv_manager.concat_csv(all_csv_wrong_dates)
df_null_citing = csv_manager.concat_csv(all_csv_null_citing)
df_null_cited = csv_manager.concat_csv(all_csv_null_cited)
df_articles_without_dois = pd.read_json(all_articles_without_dois, orient='records')
df_errors = pd.DataFrame({'type_of_error': ['null_dates', 'wrong_dates',
'null_citing', 'null_cited', 'articles_without_dois'],
'count': [sum(df_null_dates['oci']), sum(df_wrong_dates['oci']),
len(df_null_citing), len(df_null_cited),
len(df_articles_without_dois)]})