Better czech sentense is "podívej/dívej se na její dopis z března". "Viz" is too out-of-date (for me)
I have to disagree. At least in writing it is completely fine. I even used "vizte" at this very forum today.
Well, every one use other vocabulary. It´s pity, that ngrams is not in Czech, you would see. :-)
PS: "Vizte" v psaném projevu -ok. Ale pokud použije cizinec s přízvukem "viz", tak mu nikdo nebude rozumět.
We don't need no ngrams. We have the Czech national corpus http://syd.korpus.cz/dbp2I3F9.syn
Notice, that on the spoken language side the viď is used as an interjection, not as an imperative of vidět. Apparently, the imperative is not really used in the spoken language in either of the forms, but viz is alive and well in the written language. And this site is certainly not devoted only to the spoken language.