Many references have been used to create these lessons, the most important and influential ones are:

Ardalambion (The Noble Tongue)

Sindarin Dictionary of Hiswloke

Gwaith i-phethdain

Tolkien reference: History of Middle-Earth
    The Silmarillion
    The Unfinished Tales
    The Hobbit
    The Lord of the Rings

Lord of the Rings: Movies by Peter Jackson, Fran Walsh and Phillipa Boyens

Omniglot's Guide to Tengwar