A study of Gary Snyder's eco-ethic thoughts / a study of Gary Snyder's ecopoetics A study on Zhang Xunhua's economic thoughts A study of Marx's democratic thought A study on Chen Zheng's economic thoughts A study on Song Tao's economic thoughts A study on Shen Deqian's poetic thoughts A study on Wu Xuangong's economic thoughts A study of later Heidegger's aesthetics thought A study of Van Sitong's philosophical thoughts