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.
The kittens' eyes will begin to open around 7-10 days of age. Do not pry open the lids for any reason, as the immature eye is not yet ready to handle light. Some kittens will take a day to open the eyes while others will take 3-4 days. The retina matures around 5 weeks of age and the kitten sees clearly.