Advertisement expense deductibility: souvenir advertising allowed if rule 6B conditions met and expenditure is evidenced. Expenditure on advertisements in souvenirs is to be treated like other advertising expenses and may be allowed as a business deduction where it is incurred wholly and exclusively for business and the conditions of rule 6B are fulfilled, with evidence that the expenditure has been incurred; no distinction should be drawn between souvenir advertisements and other advertisements for purposes of section 37(1).