diff --git a/gregorian-calendar/gregorian-calendar-tests.ts b/gregorian-calendar/gregorian-calendar-tests.ts
new file mode 100644
index 0000000000..d364e00fd2
--- /dev/null
+++ b/gregorian-calendar/gregorian-calendar-tests.ts
@@ -0,0 +1,14 @@
+/// <reference path="../gregorian-calendar/gregorian-calendar.d.ts" />
+
+import GregorianCalendar = require('gregorian-calendar');
+import GregorianCalendarFormat = require('gregorian-calendar-format');
+
+
+let cal = new GregorianCalendar();
+cal.set(2016, 7, 27, 0, 0, 0, 0);
+
+let fmt = new GregorianCalendarFormat('yyyy-MM');
+
+let calAsStr = fmt.format(cal);
+console.log(calAsStr);
+
diff --git a/gregorian-calendar/gregorian-calendar.d.ts b/gregorian-calendar/gregorian-calendar.d.ts
new file mode 100644
index 0000000000..0bb2ffa934
--- /dev/null
+++ b/gregorian-calendar/gregorian-calendar.d.ts
@@ -0,0 +1,274 @@
+// Type definitions for gregorian-calendar v4.1.4
+// Project: https://github.com/yiminghe/gregorian-calendar
+// Definitions by: Charlie Arnold <https://github.com/cwalv>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+
+declare module 'gregorian-calendar' {
+
+    class GregorianCalendar {
+
+        constructor(locale?: Object);
+
+        /**
+         * same as call setYear, setMonth, setDayOfMonth ....
+         */
+        set(year: Number, month: Number, dayOfMonth: Number,
+            hourOfDay: Number, minutes: Number, seconds: Number,
+            milliseconds: Number): void;
+
+        /**
+         * set absolute time for current instance
+         */
+        setTime(time: Number): void;
+
+        /**
+         * get absolute time for current instance
+         */
+        getTime(): Number;
+
+        /**
+         * set current date instance's timezone offset (in minutes)
+         */
+        setTimezoneOffset(timezoneOffset: Number): void
+
+        /**
+         * current date instance's timezone offset (in minutes)
+         */
+        getTimezoneOffset(): Number;
+
+        /**
+         * set the year of the given calendar field.
+         */
+        setYear(year: Number): void;
+
+        /**
+         * Returns the year of the given calendar field.
+         */
+        getYear(): Number;
+
+        /**
+         * set the month of the given calendar field. January is 0, you can use enum
+         */
+        setMonth(month: Number): void;
+
+        /**
+         * set the month of the given calendar field without influence month.
+         * 2015-09-29 -> setMonth(2) -> 2015-03-01
+         * 2015-09-29 -> rollSetMonth(2) -> 2015-02-28
+         */
+        rollSetMonth(month: Number): void;
+
+        /**
+         * Returns the month of the given calendar field.
+         */
+        getMonth(): Number;
+
+        /**
+         * set the day of month of the given calendar field.
+         */
+        setDayOfMonth(day: Number): void;
+
+        /**
+         * Returns the day of month of the given calendar field.
+         */
+        getDayOfMonth(): Number;
+
+
+        /**
+         * set the hour of day for the given calendar field.
+         */
+        setHourOfDay(hour: Number): void;
+
+        /**
+         * Returns the hour of day for the given calendar field.
+         */
+        getHourOfDay(): Number
+
+        /**
+         * set the minute of the given calendar field.
+         */
+        setMinutes(minute: Number): void;
+
+        /**
+         * Returns the minute of the given calendar field.
+         */
+        getMinutes(): Number;
+
+        /**
+         * set the second of the given calendar field.
+         */
+        setSeconds(second: Number): void;
+
+        /**
+         * Returns the second of the given calendar field.
+         */
+        getSeconds(): Number;
+
+        /**
+         * set the millisecond of the given calendar field.
+         */
+        setMilliSeconds(second: Number): void;
+
+        /**
+         * Returns the millisecond of the given calendar field.
+         */
+        getMilliSeconds(): Number;
+
+        /**
+         * Returns the week of year of the given calendar field.
+         */
+        getWeekOfYear(): Number;
+
+        /**
+         * Returns the week of month of the given calendar field.
+         */
+        getWeekOfMonth(): Number;
+
+        /**
+         * Returns the day of year of the given calendar field.
+         */
+        getDayOfYear(): Number;
+
+        /**
+         * Returns the day of week of the given calendar field. sunday is 0, monday is 1
+         */
+        getDayOfWeek(): Number;
+
+        /**
+         * Returns the day of week in month of the given calendar field.
+         */
+        getDayOfWeekInMonth(): Number;
+
+        /**
+         * add the year of the given calendar field.
+         */
+        addYear(amount: Number): void;
+
+        /**
+         * add the month of the given calendar field.
+         */
+        addMonth(amount: Number): void;
+
+        /**
+         * add the day of month of the given calendar field.
+         */
+        addDayOfMonth(amount: Number): void;
+
+        /**
+         * add the hour of day of the given calendar field.
+         */
+        addHourOfDay(amount: Number): void;
+
+        /**
+         * add the minute of the given calendar field.
+         */
+        addMinute(amount: Number): void;
+
+        /**
+         * add the second of the given calendar field.
+         */
+        addSecond(amount: Number): void;
+
+        /**
+         * add the millisecond of the given calendar field.
+         */
+        addMilliSecond(amount: Number): void;
+
+        /**
+         * Returns the week number of year represented by this GregorianCalendar.
+         */
+        getWeekYear(): Number;
+
+        /**
+         * Sets this GregorianCalendar to the date given by the date specifiers - weekYear, weekOfYear, and dayOfWeek.
+         * weekOfYear follows the WEEK_OF_YEAR numbering.
+         * The dayOfWeek value must be one of the DAY_OF_WEEK values: SUNDAY to SATURDAY.
+         *        weekYear: the week year
+         *         weekOfYear: the week number based on weekYear
+         *         dayOfWeek: the day of week value
+         */
+        setWeekDate(weekYear: Number, weekOfYear: Number, dayOfWeek: Number): void;
+
+        /**
+         * Returns the number of weeks in the week year
+         */
+        getWeeksInWeekYear(): Number;
+
+        /**
+         * Returns a clone of current instance
+         */
+        clone(): GregorianCalendar;
+
+        equals(other: GregorianCalendar): boolean;
+
+        /**
+         * compare this object and other by day. return -1 0 or 1
+         */
+        compareToDay(other: GregorianCalendar): Number;
+
+        /**
+         * clear all field of current instance
+         */
+        clear(): void;
+    }
+
+    export = GregorianCalendar;
+}
+
+declare module 'gregorian-calendar-format' {
+
+    import GregorianCalendar = require('gregorian-calendar');
+
+    enum DateTimeStyle  {
+        /**
+         * full style
+         */
+        FULL = 0,
+        /**
+         * long style
+         */
+        LONG,
+        /**
+         * medium style
+         */
+        MEDIUM,
+        /**
+         * short style
+         */
+        SHORT,
+    }
+
+    class DateTimeFormat {
+
+        public Style: DateTimeStyle;
+
+        /**
+         * @param pattern The format pattern string
+         * @param locale The local of to output (defaults to require('gregorian-calendar/lib/locale/en_US'),
+         *               may also be one of:
+         *                   require('gregorian-calendar/lib/locale/zh_CN')
+         *                   require('gregorian-calendar/lib/locale/ru_RU')
+         */
+        constructor(pattern: string, locale?: Object);
+
+        /**
+         * format an instance of GregorianCalendar according to pattern
+         */
+        format(calendar: GregorianCalendar): String;
+
+        /**
+         * parse a dateString to an instance of GregorianCalendar according to pattern, it's better to specify calendarLocale, such as
+         *  `df.parse('2013-11-12', {locale: require('gregorian-calendar/lib/locale/zh_CN'}));`
+         */
+        parse(dateString: String, {locale: Object}): GregorianCalendar;
+
+        /**
+         * get a predefine GregorianCalendarFormat instance
+         */
+        getDateTimeInstance(dateStyle: DateTimeStyle, timeStyle: DateTimeStyle, locale?: Object): DateTimeFormat;
+    }
+
+    export = DateTimeFormat;
+}
+