Ved Extracts

The main content of every ved, which is considered shruti, is called Samhita. Samhita should translate as "collection". Each Ved [i.e. Samhita] is organized in terms of "Mandals", which are organized in terms of Sukt, which contains Mantras.
Thus Samhita contains Mandals, which contains Sukts, which contains Mantra. In some cases, Mandals are organized as Anuvakas, which contain Sukts.
To explain the contents of each Ved, Rishis have created Brahmans, Aranyaks and Upanishads. However some Brahmans, Aranyaks and Upanishads are not directly related to a specific ved, for some the linkage is not known as well as many are not available.
The table below lists such Brahmans, Aranyaks and Upanishads, which can't be linked to a specific Ved. 

Brahman Aranyak Upanishad
Brahm Vidya Gyan Vidya Sadhna Vidya
Aaruney ??  Atmapuj Pranav Gaytri Rahsya
Saulabh   Dvay Shiv Sankalp Chaturved
Shailali    Svasamband   Tulasya 
Parashar        Nrisinh Shatchakra 
Maashashraani        Yograj 
Kaapey        Radha 
 Rahasyaamnaay       Rudra 
Nirukt        Ladgul 
A few other unkowns        

There are some Brahmans, Aranyaks and Upanishads related to specific Ved but not available. These are listed with the respective Ved.

Please visit any of the following to learn more:

Link Comments
Veda : Sanskrit Documents  Has many vedic books, in many languages, with commentary from many scholars. Also audio of many mantras
sanskritweb  Good to read the vedic books - in sections. This link will directly take you to Yajur Ved page.
Hindupedia This link takes you directly Veda page of the site. The website has many more content and worth a visit.