1390-6542
1390-6542
S1390-65422018000400088
10.29019/enfoqueute.v9n4.400
Ecuador
00
12
2018
00
12
2018
9
4
88
98
[
2002
]
[
2004
]
[
2018
181-8
]
[
1988
78
7
7
674-81
]
[
2005
94
1
1
57-72
]
[
2005
21
1
1
103-12
]
[
2005
24
3
3
243-55
]
[
1997
17
1-2
1-2
185-93
]
[
2007
96
4
4
309-19
]
[
2018
19-21
]