Analysis of information sources in references of the Wikipedia article "Null pointer" in English language version.
const qualifier (§5.4) prevents accidental redefinition of NULL and ensures that NULL can be used where a constant is required.". The C++ Programming Language (14th printing of 3rd ed.). United States and Canada: Addison–Wesley. p. 88. ISBN 0-201-88954-4.{{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link){{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link){{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link){{cite book}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)