invalid date

[houshuang]

The following entry could not be parsed by citeproc. All other 1000+ entries went well, most have similar date fields:

@incollection{hrimech1998spontaneous, author = {Hrimech, M. and Bouchard, Paul}, container = {Developing paradigms in self-directed learning}, date-added = {2012-03-11 13:04:46 +0000}, date-modified = {2012-03-11 13:04:54 +0000}, editor = {Long, H. and Associates}, location = {Oklahoma, OK : Oklahoma}, pages = {27–44}, publisher = {University Press}, title = {Spontaneous learning strategies in the natural setting}, year = {1998}, bdsk-file-1 = {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} }

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'