One who, while engaged in other business, sells land for another, may recover his commissions, though he had not taken out a license as required of real estate agents, since a single sale does not constitute the exercise of the business of real estate brokerage. O'Neill v. Sinclair, 153 I11. 525, 39 N. E. 124; Black v. Snook, 204 Pa. St. 119, 53 A. 648; Yedinsky v. Strouse, 6 Pa. Super. Ct. 587, 42 W. N, C. 12; Jones v. Mo. Lumber & Mining Co., 166 I11. App. 266; Glicken v. Shaller, 185 I11. App. 115; Greenburg v. Nyberg Au. Whs., 162 I11. App. 504; Lake v. Kontsojiania, 174 I11. App. 252; Woods v. Heron, 78 A. 1128, 229 Pa. 625.