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Olumbe, R. S. (2019). Children’s Ministry: Students’ Manual. The Fraser Peckham Trust: Worcestershire, UK
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Olumbe R., Mumo, M., Karanu, D., Nyandiega, K. and Leperon, M. (2019). Christian Religious Education: Pupils Activity Book, Grade 4.
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Olumbe et. al. In Department of Children Services (2016). National Psychosocial Support Guidelines For Orphans and Vulnerable Children in Kenya (Popular Version). Nairobi, Kenya
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Olumbe et. al. In Department of Children Services (2015). National Psychosocial Support Guidelines For Orphans and Vulnerable Children in Kenya. Nairobi, Kenya
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Olumbe, R. et. al, (2007). Course Book for Chaplaincy Studies Term Four. THE 231: Principles of Christian Counselling: Nairobi, Kenya.
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Olumbe, R. et. al, (2007). Course Book for Chaplaincy Studies Term Four. THE 232: Counselling and Drug Abuse: Nairobi, Kenya.
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Olumbe, R. et. al, (2007). Course Book for Chaplaincy Studies Term Four. THE 233: Counselling and Conflict Resolution: Nairobi, Kenya.
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Oladipo, R., Esther, H. M., Manya, S., Nzyuko, S., Olumbe, R., Mogute-Nyangera, M., & Mutunga, D. (Eds.). (2015). A Modern Approach to Positive and Responsive Parenting. Nairobi, Kenya: Daystar University.
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Olumbe, R. (2013). Understanding Aspects of the African Culture and their Effect on the Child’s Faith. In S. Greener, R. Oladipo, A. Munene, H. Malinda, S. Nzyuko, F. Nguru, ... Bowen, Christian Perspectives and Research on child Development in the African Context. (pp. 232–243). Nairobi, Kenya: 4 Daystar University.