Yevamos 35b-36b
After a man dies without children, how long must the surviving brothers and widows wait before consummation or severance of their Zika bond? \u2022 If they did not wait and engaged in Yibum or Chalitzah, what are the ramifications? \u2022 If the widow has an ectopic pregnancy may she immediately sever the levirate bond? \u2022 How must a will be structured to be halachically valid? \u2022 Fructus rights in halacha