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Diagram of the nasal passage and sinuses. [For illustrative purposes only.] From Intranasal Drug Administration — An Attractive Delivery Route for Some Drugs by Degenhard Marx, Gerallt Williams and Matthias Birkhoff (http://dx.doi.org/10.5772/59468). Use of the figure does not assert or imply any connection with, sponsorship or endorsement by the Original Authors and is subject to Creative Commons License 3.0 (https://creativecommons.org/licenses/by/3.0/legalcode)
