List of Articles Cost efficiency Open Access Article Abstract Page Full-Text 1 - Allocation models for DMUs with negative data Ghasem Tohidi Maryam Khodadadi Open Access Article Abstract Page Full-Text 2 - Estimating multi-period global cost efficiency and productivity change of systems with network structures S. Tohidnia G. Tohidi 20.1001.1.17355702.2020.16.1.11.4