Validating A Surname

I need to validate a surname field which obviously can only consist of letters and occasionally spaces and/or hyphens. (i.e. van Driel or Johnson-Crooks)

I managed to create a validation rule which would allow me to have space in the surname field:

Is Null Or Not Like "*[!((a-z) or ( ))]*"

but when I tried to allow hyphens into the field - I used these codes - but none of them worked:


Is Null Or Not Like "*[!((a-z) or ( ) or (-))]*"

Is Null Or Not Like "*[!(a-z)]*" Or Not Like (" ") Or Not Like ("-")

Is Null Or Not Like "*[!(a-z)]*" Or Not Like "*[!( )]*" Or Not Like "*[!(-)]*"

Is Null Or Not Like "*[!(a-z)]*" Or Like "*[!( )]*" Or Like "*[!(-)]*"

Is Null Or Not Like "*[!(a-z)]*" Or Not Like "*[( )]*" Or Not Like "*[(-)]*"

Is Null or Not Like "*[!(a-z)]*" or (in ("-"," "))

Is Null Or Not Like "*[!(a-z)]*" And (Not In ("*[0-9]*"))

Is Null Or Not Like "*[!(a-z)]*" And (Not In ("*[0-9]*")) And (In ("-"," "))

Is Null Or Not Like "*[!(a-z)]*" Or Like ( ) Or (-)


Please can smeone help me.

James