S. 69C : Unexplained expenditure-Accommodation entries-Grey market-Trading of electronic items-Information from sales tax department-Summons to parties returned unserved-Tribunal restricting the disallowance to three percent of purchases-Order of Assessing Officer disallowing the peak of purchases-CIT(A) and Tribunal estimated the percentage of alleged bogus purchases-On appeal by revenue-Court held that reassessment Notice valid-Failure to quote legal provision or quoting not to vitiate an action if power and authority were to be otherwise found in statute-Order under section 143(3), read with section 147 of the Act passed by the Assessing Officer was restored. [S. 37(1), 133(6),143(1)), 147, 148, 260A]