What are the texts of Vajrāyana Buddhism? And where can I get? What are the scriptures of Vajrāyana Buddhism? Or texts related? 
Where can I get scriptures or texts on Vajrāyana Buddhism?
This person – Andrea Pema will be able to help you on this. If asked just say that Saptha Visuddhi referred you to him.
Andrea Pema has translated many of  Vajrāyana Buddhism text to English. The follow are few of his notes:

The Progressive Stages of Meditation. From Shamata to the Beginning of the Mahasandhi

An Excerpt from my Book “Buddha Dharma”: Introduction to the Vajrayana (for Advanced Yogis and Yoginis as well as for Beginners)

On the three Buddha Bodies - the Buddhist Sutra and Tantra on the Qualities of Enlightenment

The Guru Yoga Practice of Padmasambhava, for Beginners and Advanced Practitioners

A short advice on how to do Deity Yoga in Buddhist Tantra

What is “Bodhicitta” in the Tantra ?

A Gem of Compassion from the Mahayana; The Practice of Tonglen, a “must” for those that follow the Bodhisattva Path

The Dharani of Lapis Light that generates the Power of the Tathagatas Meditative Absorption

On Shunyata ( Emptiness)

On meditation and sacred outlook

The Path of Bliss in Buddhist Tantra