Where can I get augur mods in Warframe?

Excuse me, could you please clarify where exactly one might be able to acquire augur mods within the game of Warframe? I've been searching for them and have had some difficulty locating them. Are there specific missions or activities that reward these mods, or is there a particular vendor or marketplace where they can be purchased? I'm eager to enhance my gameplay experience with these valuable items, so any information you could provide would be greatly appreciated.