How to start with Shaivam??

Hello shaiva brothers

I am a vaisnava and very much attached to Krishna. However my younger sister is very much attached to Shiva and she likes to worship Shiva but doesn't have any philosophical (jnana) on Shaivam.

Generally it is easier to find resources to study on Vaishnava.

Are there any resources (English will be appreciated) for my sister to follow Shaivam. Are Himaliyan academy books good? What are the primary texts of Shaivam and are they available in English (like for example Vaishnava it will be Gita, Bhagvata/Visnu Purana,Brahm sutra,Upanisads)