Effect of marijuana smoking on lung function change in older ever tobacco smokers.

Barjaktarevic I, Cooper CB, Shing T, Buhr RG, Hoffman EA, Woodruff PG, Drummond MB, Kanner RE, Han MK, Hansel NN, Bowler RP, Kinney GL, Jacobson S, Morris MA, Martinez FJ, Ohar J, Couper D, Tashkin DP