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How can I typeset the symbol for the reduced Planck constant (from quantum theory)? It consists in an italic "h" whose upper part is crossed by a small "slanted" bar:
For information, this slanted bar also occurs quite often with the letter "l" (ell) in Polish. Example: the Polish word for "word" is "slowo", where the letter "l" bears a slanted little bar.
Is there a package that provides that symbol?
Second question: please tell me where to look for and how to correct the LaTex PDF warning
overfull/underfull \hbox or \vbox