@article {11489,
	title = {Crossed modules and the integrability of Lie brackets},
	year = {2005},
	abstract = {<span>We show that the integrability obstruction of a transitive Lie algebroid coincides with the lifting obstruction of a crossed module of groupoids associated naturally with the given algebroid. Then we extend this result to general extensions of integrable transitive Lie algebroids by Lie algebra bundles. Such a lifting obstruction is directly related with the classification of extensions of transitive Lie groupoids. We also give a classification of such extensions which differentiates to the classification of transitive Lie algebroids discussed in \cite{KCHM:new}.</span>},
	url = {https://arxiv.org/abs/math/0501103},
	author = {Iakovos Androulidakis}
}
