Here are some useful texts on tribology
Advances in Medical Tribology by Dowson
Advanced Strength and Applied Elasticity by Ugural and Fenster
Advanced Concepts of Bearing Technology by Harris and Kotzalas
Bearing Design in Machinery: Engineering Tribology and Lubrication by Marcell Dekker
Boundary-Layer Theory by Schlichting, Gersten, Krause, and Oertel
Contact Mechanics by Johnson
Elastohydrodynamics by Gohar
Engineering Tribology by Stachowiak and Batchelor
Essential Concept of Bearing Technology by Harris and Kotzalas
Fluid Film Lubrication: Theory and Design by Szeri
Fluid Mechanics by White
Friction Wear Lubrication: A Textbook in Tribology by Ludema
Fundamentals of Fluid Film Lubrication by Hamrock, Schmid, and Jacobson
Fundamentals of Tribology by Gohar
Handbook of Tribology by Gupta
History of Tribology by Dowson
Introduction to Tribology by Bhushan
Modern Tribology Handbook (2 Volumes) by Bhushan
Rolling Bearing Analysis (2 Volumes) by Harris and Kotzalas
Tribology in Electrical Environments by Prashad
Tribology of Mechanical Systems: A Guide to Present and Future Technologies editors: Vizintin, Kalin, Dohda, Jahanmir