Avrumi Hersh asks:
Where exactly does the gemoro yevomos darshen that yibum is also from erusin? (I know that this is the din from many places e.g. 20a but where is the exact mekor?)
Avrumi Hersh, London england
The Kollel replies:
The Gemara in Yevamos 13b learns it from the word "Chutzah".
Kollel Iyun Hadaf