1978  The great vow in India and Tibet: an ethnological inquiry, Rotterdam.
– Numen: Natur und Transzendenz: Versuch einer religiösen Anthropologie, Rotterdam.
1980  Ādiśeṣa: the essence of the Supreme Truth (Paramārthasāra), Sanskrit text with translation and notes, Leiden: Brill (Religious Texts Translation Series Nisaba 10).
1981  ‘Ignorance’ and ‘Supreme Truth’ according to Śaṅkara’s commentaries on the Bṛhadāraṇyaka-Upaniṣad and Chāndogya-Upaniṣad; texts, translations, and explanatory comments, with introduction, bibliography, and word index, Leiden [s.n.] – PhD thesis Leiden University.
– ‘Ignorance’ and ‘supreme truth’ according to Śaṅkara’s commentary on the Bhagavad-Gītā, Leiden: [s.n.]. – typoscript.
1984  Review of: J. Kattackal, Religion and ethics in Advaita, Freiburg etc. 1980. WZKS 28: 230-233.