"Monthly Output Index for the U.S. Transportation Sector", (with H. Stekler, P. Young and W. Yao), Journal of Transportation and Statistics, Vol. 6 (2/3), 1-41, 2003.

"The Predictive Power of an Experimental Transportation Output Index," (with W. Yao), Applied Economic Letters, Vol. 11, 3, 2004, 149-152.

"Transportation Sector and the Aggregate Economy: Their Linkages at the Business Cycle Frequencies", (with W. Yao), Transportation Research Record, National Academies, 103-111, 2004.

"A Dynamic Factor Model of the Coincident Indicators for the U.S. Transportation Sector," Applied Economics Letters, (with V. Yao), 11, 595-600, 2004.

"Economic Indicators for the U.S. Transportation Sector" (with Vincent Yao), Transportation Research - A, 40, 2006, 872-887.

"Should Transportation Output be Included as Part of the Coincident Indicators System?"(with W. Yao), OECD Journal: Journal of Business Cycle Analysis and Measurement, Forthcoming,  2012/1.