There are three types of Monday fast.

    1. Simple every Monday fast is practiced to propitiate Lord Shiva and Parvati. The panchakshari
        Mantra "Om Namah Shivaya" should be  repeated on this day.
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    2. Som pradosh fast
http://shivadurga.blogspot.com/search/label/Pradosh
    3. 16 weeks Monday fast.
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