regexp поиск по части текста [требует правки]

День добрый! Есть кусок кода:

                        ["September, 2014", 347301542],
                        ["December, 2014", 350009195],
                        ["March, 2015", 358699477],
                        ["June, 2015", 353522656],
                        ["September, 2015", 354694635],
                        ["December, 2015", 359624486],
                        ["March, 2016", 363391484],
                        ["June, 2016", 360143090],
                        ["September, 2016", 364766739],
                        ["December, 2016", 365020738],
                        ["March, 2017", 376799612]
                    ],
                    "acct_083": [
                        ["Period", "Value"],
                        ["September, 2015", 38010],
                        ["December, 2015", 38036],
                        ["March, 2016", 37922],
                        ["June, 2016", 37819],
                        ["September, 2016", 37931],
                        ["December, 2016", 38048],
                        ["March, 2017", 38129]
                    ],
                    "acct_566": [
                        ["September, 2004", 11],
                        ["December, 2004", 11],
                        ["March, 2005", 11],
                        ["June, 2005", 11],
                        ["September, 2005", 10],
                        ["December, 2015", 8],

Мне необходимо вытащить из куска между "acct_083" и "acct_566" в данном случае ["December, 2015", 8],.