Info on Knoll Credenza  

I purchased a vintage Knoll credenza in 2002.  Was hoping to get some help with the following:-production year (or range of years)-type of wood-material type of top-rarity of top (most vintage Knoll credenzas I find online have marble tops)I bought it with two of the metal drawer pulls missing.  Any suggestions on where to source replacements?I'm also curious about how best to estimate the value.  Note, per the forum rules, I'm not asking for actual valuation.  Rather, just hoping to get suggestions on how to go about estimating value.Thanks.
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