For instance (DaSilva, theorem 3.1).
Moreover, tubular neighbourhoods are unique up to homotopy in a suitable sense:
This appears as (Godin, prop. 31).
Basics on tubular neighbourhoods are reviewed for instance in
Stanley Kochmann, section 1.2 of Bordism, Stable Homotopy and Adams Spectral Sequences, AMS 1996
The homotopical uniqueness of tubular neighbourhoods is discussed in
For an analogue in homotopical algebraic geometry see