checks
    | newEntries newFields newMacros toBeDeleted toBeInclude error |

    macros := OrderedCollection new.
    macrosUsage := Dictionary new.
    entries := OrderedCollection new.

    errorStream := WriteStream on: String new.
    [eof] whileFalse: [ self bibtexBlockToCZEntry: self getBibtexBlock ].

    newEntries := OrderedCollection new.
    macroKeys := macros collect: [ :each | each key key ].

    entries do: [ :assoc |
        toBeInclude := true.
        error := false.

        "checks if the type of the entry is a correct bibtex type"
        (self checkBibtexType: assoc key)
            ifFalse: [
                error := true.
                toBeInclude := false ].

        newFields := OrderedCollection new.
        fieldKeys := OrderedCollection new.
        assoc key fields do: [ :field |
            toBeDeleted := false.

            "checks the macros referenced in the entry and removes fields with undefined macros"
            (self checkMacroReferenced: field)
                ifFalse: [ toBeDeleted := true ].

            toBeDeleted ifFalse: [
                "removes empty fields"
                (self checkEmptyField: field)
                    ifFalse: [ toBeDeleted := true ] ].

            "removes duplicate fields"
            (self chechDuplicateField: field)
                ifFalse: [ toBeDeleted := true ].

            toBeDeleted
                ifFalse: [ newFields add: field ]
                ifTrue: [ error := true ]
        ].
        assoc key fields: newFields.

        "checks if the entry contains all the fields needed by it's type"
        ((typeFieldsMatching at: (assoc key type)) value: (assoc key fields collect: [ :each | each key ]))
            ifFalse: [
                errorStream nextPutAll: 'Error: Entry does not contain all needed fields'; cr.
                error := true.
                toBeInclude := false ].

        "checks if the key is unique and changes it if it's not"
        keys at: assoc key key put: ((keys at: assoc key key ifAbsent: 0) + 1).
        ((keys at: assoc key key) > 1)
            ifTrue: [ | key |
                key := assoc key key.
                assoc key key: '###',(assoc key key, '_',(keys at: assoc key key) asString,'###' ).
                errorStream nextPutAll: 'Warning: duplicate key: ', key, ' changed to: ', assoc key key; cr.
        error := true ].

        "checks if the entry respects all the rules"
        rules do: [ :rule |
            (rule value value: assoc key)
                ifFalse: [
                    errorStream nextPutAll: 'Error : entry does not respect the rule: ', rule key; cr.
                    error := true.
                    toBeInclude := false ] ].

        "displays the errors and creates the collection with safe entries"
        error ifTrue: [
            errorStream nextPut: Character tab; nextPutAll: 'for :'; cr; nextPutAll: assoc value; cr.
            toBeInclude
                ifTrue: [
                    newEntries add: assoc key.
                    errorStream nextPutAll: '(There are only warnings, the entry is not deleted)'; cr; cr ]
                ifFalse: [
                    errorStream nextPutAll: '(There are errors, the entry is deleted)'; cr; cr ]
        ]
    ].

    "removes unused macros"
    newMacros := OrderedCollection new.
    macros do: [ :assoc |
        (macrosUsage at: assoc key key)
            ifFalse: [ errorStream nextPutAll: 'Unused macro:'; cr; nextPutAll: assoc value; cr; cr ]
            ifTrue: [  newMacros add: assoc ]
    ].
    macros := newMacros