Thanks for the compliments friends.
Yes, the technique is to really thickens the vocals like the Beatles did as Tony said.

I used wav file format to record to minimized sonic losses due to multiple overdubbings. I don't have a multitrack recorder so I just used my SD9 to record and used it's voicetron for harmony. You can use any vocal processing/harmony equipment to record.

Steps for this song:
1) I used a quality backing track of this song
2) I recorded the backing track with first vocal harmony
3) I overdubbed the previous recording with another vocal harmony (slightly different type)
4) Finally, I overdubbed with lead vocal with unison vocal effect

Result is a very thick choir-like vocals

Hope this helps.