This article presents a series of recent studies on the mistakes and difficulties - leading to mistakes - that are manifested at every linguistic level: phonetic, morphologic, syntactic, lexical and semantic. Among the studies described here, there are dictionaries as well as other books written in a form resembling dictionaries to a greater or lesser extent, which discuss different aspects of standard language. The main section dedicated to these studies is preceded by a short overview presenting the preoccupations for the standardization of Romanian. The overview implicitly refers to aspects that facilitate understanding the relation between norm and deviation from the norm, language dynamics and the norm itself.