Please note that within this document, the term "Tzitzit" refers to the fringe-strings which are worn on the corners of four-cornered garments.
Dyeing the "white" strings to be the same color as the garment: Menachot 41b
The white strings as the holier Strings: Menachot 39a [See Rashi]
Whether Tzitzit are valid without the White Strings: Menachot 38a-b
Whether White Strings must precede the Techelet, or this is just the ideal format: Menachot 38a-b
It is worse to not have the white strings than to not have the Techelet-dyed strings, because the white strings are easier to get: Menachot 43b