Besides editing The Moslem World, a quarterly scholarly periodical – 37 vols.(1911-47), and the Quarterly Review (London), he wrote the following books:
Arabia, the Cradle of Islam (1900) – [1]
Topsy Turvy Land (1902), with his wife, Mrs. Amy E. Zwemer
Raymond Lull (1902)
Moslem Doctrine of God (1906)
The Mohammedan World of Today (1906)
Islam: a challenge to faith: studies on the Mohammedan religion and the needs and opportunities of the Mohammedan world (1907)
Our Moslem sisters : a cry of need from lands of darkness interpreted by those who heard it, (1907) — edited with Annie van Sommer
The Moslem World (1908)
The Nearer and Farther East: Outline studies of Moslem lands, and of Siam, Burma, and Korea (1908), with Arthur Judson Brown
The Unoccupied Mission Fields (1910)
The Moslem Christ (1911)
The Unoccupied Mission Fields of Africa and Asia (1911)
Daylight In The Harem: A New Era For Moslem Women (1911) — Papers on present-day reform movements, conditions and methods of work among Moslem women read at the Lucknow Conference
Zigzag Journeys in the Camel Country (1912)
Childhood in the Moslem World (1915)
Mohammed or Christ? (1916)
The Disintegration of Islam (1916) — student lectures on missions at Princeton TS
A Moslem Seeker after God ... showing Islam at its best in the life and teaching of Al-Ghazali (1920)
The Influence of Animism on Islam : An Account of Popular Superstitions (1920)
The Law of Apostasy in Islam (1924)
Moslem Women (1926), with his wife, Mrs. Amy E. Zwemer
The Glory of the Cross (1928)
Across the world of Islam (1929)
The exalted name of Christ (1932), translated from Arabic by Oskar Hermansson and Gustaf Ahlbert, assisted by Abdu Vali Akhond
Thinking Missions with Christ (1934)
Taking hold of God : studies on the nature, need and power of prayer (1936)
It's Hard To Be A Christian : Some Aspects of the Fight for Character in the Life of the Pilgrim (1937)
Solitary Throne, addresses Given at the Keswick Convention on the Glory and Uniqueness of the Christian Message (1937)
The Golden Milestone : Reminiscences of Pioneer Days Fifty Years in Arabia (1938), with James Cantine
Dynamic Christianity and the World Today (1939)
Studies in Popular Islam : A Collection of papers dealing with the Superstitions & Beliefs of the Common People (1939)
The Glory of the Manger: Studies on the Incarnation (1940)
The Art of Listening to God (1940)
The Cross Above the Crescent (1941)
Islam in Madagascar (1941)
Into All the World (1943)
Evangelism Today: Message Not Method (1944)
The Origin of Religion : Evolution or Revelation (1945) — based on the Smyth Lectures 1935
Heirs of the Prophets (1946)
A factual survey of the Moslem world with maps and statistical tables (1946)
The Glory of the Empty Tomb (1947)
How Rich the Harvest (1948)
Sons of Adam : Studies of Old Testament characters in New Testament light (1951)
Social And Moral Evils Of Islam (2002) — reprint of an earlier work
He also wrote an article describing his travels in Oman and the Trucial Coast (now U.A.E.), which famously features the earliest known photograph of the Qasr al-Hosn in Abu Dhabi:
Three Journeys in Northern Oman (1902), The Geographical Journal, Vol XIX, No1
http://en.wikipedia.org/wiki/Samuel_Marinus_Zwemer