Crossword puzzle clue "let know"

Lyricist Cahn who wrote "Let It Snow! Let It Snow! Let It Snow!"

"Let It Snow, Let It Snow, Let It Snow" composer

Line from ''Let It Snow! Let It Snow! Let It Snow!''

You know -- know

"Someone I know wants to know (and that someone is me)"

"I know! I know!"

Sylvia Plath poem that begins "I know the bottom, she says. I know it with my great tap root"

"Demand me nothing: what you know, you know: From this time forth I never will speak word" is his last line