The Collaborative International Dictionary of English v.0.48:

Attributable \At*trib"u*ta*ble\, a.
   Capable of being attributed; ascribable; imputable.
   [1913 Webster]

         Errors . . . attributable to carelessness. --J. D.
                                                  Hooker.
   [1913 Webster]

WordNet (r) 3.0 (2006):

attributable
    adj 1: capable of being attributed; "the collapse of the
           movement was attributable to a lack of morale"; "an idea
           attributable to a Russian" [ant: unascribable,
           unattributable]

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "attributable":
   accountable, alleged, arising from, ascribable, assignable,
   attributable to, attributed, caused by, charged, coming from,
   contingent on, credited, dependent on, derivable from,
   derivational, derivative, deserving, due, due to, entitled to,
   explicable, imputable, imputed, meriting, meritorious,
   occasioned by, owing, owing to, putative, referable, referred to,
   resulting from, traceable, worthy of