X windows library missing
 

Hi,
Can anyone tell me in which library of X windows following functions are defined?
XwTextCopyBuffer
XuInsertCursor
XuRemoveCursor
XuInsertNewLine
XwTextSetInsertPos
XwtexteditWidgetClass
XwTextReplace
XwTextClearBuffer
Or to put it in other way, which library I should include in my Makefile in order to avoid "Undefined symbol" error related to above mentioned functions?
Thanks
Smitha