The UK's Wildlife Heritage Foundation announced the birth of four Pallas's Cat kittens on May 28th to proud parents Tula (F) and Wei Shand (M). Tula is doing a fabulous job of caring for all her new kittens and they are growing up very fast!  In the following videos the kittens can be seen at 5 days old and then 3 weeks old, which helps give you an idea of how quickly these kittens are developing. 

Note that what appears to be hissing in the second video is actually the kittens smelling the keepers when they come to check-in. The WHF explains that they are actually quite relaxed and this open-mouthed smelling behavior dissipates as they get older.

UPDATE: Just got this new video in along with new instructions - #1) Avoid bright light #2) Don't get them wet and #3) NEVER feed them after midnight.