Tantra Sāra 1.028
śaṅkhacakragadāpadmadharāścaitē hi sarvaśaḥ। kramavyutkramapadmādi gadādivyutkramastathā। ardhakramaḥ sāntaraśca ṣaṭsu ṣaṭsvaripūrviṇām ॥28॥
They are all (24 forms) carrying conches, discs, clubs, and lotuses always. They are holding lotus in order and then in reverse order, then the club in reverse order, then in half order, then in intervals, grouped in six of the six preceding six vowels.
Note:
A pictorial representation of 24 forms is the order described:
