How should I record my business transactions? Purchases, sales, payroll, and other transactions you have in your business generate supporting documents. These documents contain information you need to record in your books. What is the burden of proof? The responsibility to substantiate entries, deductions, and statements made on your tax returns is known as the burden of proof.
Mice will probably open their eyes when they're about 10-14 days  old. About the time the hair is fully covering them they open their  eyes.
Kittens open their eyes about seven to ten days after birth. At first, the retina is poorly developed and vision is poor. Kittens are not able to see as well as adult cats until about ten weeks after birth. Kittens develop very quickly from about two weeks of age until their seventh week.