Identify the items from the following list that are likely to serve as source documents.

$\backslash$table$[[$Item$,\backslash$table$[[$Is this a$],[$source$],[$document$?]]],[$a$.$ Invoice from supplier,$],[$b$.$ Ledger,$],[$c$.$ Statement of cash flows,$],[$d$.$ Company revenue account,$],[$e$.$ Employee time clock record,$],[$f$.$ Prepaid insurance account,$],[$g$.$ Income statement,$],[$h$.$ Purchase order,$],[$i$.$ Telephone bill,$]]$