Is it true that Allah has already chosen our marriage partners before we are born? If so, where can I find information on this and othere related articles?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Fifty thousand years before creation, Allah, The Exalted, has decreed and written in 'al-lauh al-Mahfoodz' (The preserved Tablet) all what would happen in the universe as recorded in Sahih Muslim.
Choosing a spouse is included in the above-stated generalization. This is part and parcel of our belief, i.e. in 'al-Qadaa and al-Qadar'. So, we advise you to consult the book of 'Ma'arej al-Qabool', written by Hafiz al- Hakmi and the book of 'al-Iman Bil-Qadaa Wal-Qadar Wa Atharahu 'Ala Soluk al-Insaan' by 'Abdul Karim Zaidan .
Allah knows best.