The "proper" spellings would be in Cyrillic, and for those just see the entries here:
Nikolai,
Aleksandra,
Olga,
Tatyana,
Mariya,
Anastasiya, and
Aleksey.
Those Latin spellings, btw, are generally considered the proper Romanisations of these particular Cyrillic names. However, more often than not I've seen
Mariya and
Anastasiya rendered without the Y.
Miranda

Proud adopter of 15 punctuation marks; see my profile for their names.