Gross misinformation
Look:
I don't care where you took this chart from, remember well: Bulgarian has six vowels, SIX, SIX, SIX and NOT eight. There are four other allophones (two between a and @ and two between o and u), which appear in unstressed syllables depending on the position of the unstressed syllable to the stressed syllable within a certain word. If you are posting also allophones and not only phonemes (the reasonable question is why you are doing this but we'll deal with this some other time), then the vowel chart should include all ten of them and not only eight with information which is an allophone and which is a phoneme. But you don't know that, do you?

Then we get to another reasonable question: why do you think that you can erase the whole vowel section with the vowel descriptions? Ha? 

So: you post a chart which is WRONG and then you erase a section which is RIGHT. What the hell are you doing? I am getting tired of non-experts who read something somewhere and then come and try to wreak havoc on articles which they understand nothing about. A couple of months ago, one user was trying to change the article Bulgaria because he had read that the Bulgarians were descendants of the Shumers. In two words, your edit is pretty much of the same value and worth. For the phonetics section here, I've used the Routledge compendium on Slavic languages (1991) and the newest Bulgarian edition of New Bulgarian - phonetics, grammar and syntax. Please, consult any book on Bulgarian phonetics before you come again with this vowel chart.