Dictionary - she knows the language so I don't think so. Encyclopedia - that's the first thing she should take a look at Card catalog - probably yes if she wants to know what's stored at local libraries Music index - it might come in handy when writing about Iowa's culture, but I don't think it's necessary for her Librarian gazetteer - it could help her to find out some info about most crucial regions Telephone - if she's not sure of something she found out in other sources, she might want to use a phone and ask for further assistance herself Directory - it shouldn't be necessary - all important info shoul be found in other sources Vertical file - sure, it's always a rich source of various info Thesaurus - I don't think she would need that for anything
I hope that's more less what you asked for :)
The reference materials that would probably not be helpful for Linda's research paper about Iowa are the dictionary, music index, telephone directory, and thesaurus, as they do not provide relevant information about the state.
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