How To Notate Vibrato?

As many of you might have noticed, vibrato is a really common practice between string players in general. What really surprised me today, is that i did not find any "official" ways of notating vibrato, other than writing "vib" over a note.

The problem with that is when i have multiple vibrato notes, text can take a lot of space. Would it be valid if i simply placed a note with a different head in the beginning of the score and wrote the meaning right next to it?

Example :   NOTE WITH TRIANGULAR HEAD = VIBRATO

String players usually apply vibrato to all notes automatically (no special notation required). When a composer wants a passage to be played without vibrato, they usually write no vibrato (or senza vib. or something similar). 

Some modern scores use a graphical notation to indicate specific intensity and changes in vibrato in the form of a wave above the staff. Otherwise written performance directions are the norm. You could use a line to indicate a group of notes as with or without vibrato, as you might an 8va or a ritardando.