found: Work cat.: Hoogesteger, J. Tree ring dynamics in mountain birch, 2006:p. 8 (the mountain birch Betula pubescens ssp. czerepanovii (formerly called B. pubescens ssp. tortuosa or B. tortuosa))
found: GRIN taxonomy for plants, via WWW, Mar. 1, 2007(Betula pubescens Ehrh. subsp. tortuosa; common name: mountain birch; synonyms: Betula czerepanovii, Betula pubescens subsp. czerepanovii, Betula tortuosa)
found: Oxfordjournals.org website, June 8, 2007(Mountain birch (Betula pubescens ssp. czerepanovii))
notfound: The plants database, Mar. 1, 2007;UNEP-WCMC species database - trees, Mar. 1, 2007;Mansfeld's world database of agricultural and horticultural crops, Mar. 1, 2007