Multi phase LO generation

Can an RF person explain why we need multi-phase LO generation for the mixer.
I can't find an introductory resource on the subject. Any textbook reference would be really appreciated.
Thanks

It's necessary when you want to have a polyphase operation, like for SSB receivers/transmitters. The alternative is to split the RF into polyphase components, but often it's easier to do this to the LO. Just google "SSB mixer."