"Derived from sources within" 1 State or another, as applied to entire net income, means such income and gain from all property owned and from salaries, wages, or compensation for personal services of whatever kind and in whatever form paid, and from all business, trade, profession or occupation carried on, in the particular State. No person who is not a dealer holding property primarily for sale to customers in the ordinary course of his trade or business, shall be deemed to carry on a business, trade, profession or occupation in a State solely by reason of the purchase and sale of property for his own account.
N.J.S. § 54:8A-4